r/EPA
United States
Environmental Protection
Agency
Office of Radiation Programs
Las Vegas Facility
P.O. Box 15027
Las Vegas NV 891 14
ORP/LVF-79-1
November 1978
Radiation
Radioactivity in Selected
Mineral Extraction
Industries
A Literature Review
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Technical Note
ORP/LV-79-1
RADIOACTIVITY IN SELECTED MINERAL EXTRACTION INDUSTRIES
A LITERATURE REVIEW
James D. Bliss*
November 1978
U.S. Environmental Protection Agency
Office of Radiation Programs
Las Vegas Facility
Las Vegas, Nevada 89114
*Now with the U.S. Geological Survey, 920 National Center, Reston, VA 22092
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PREFACE
The Office of Radiation Programs of the Environmental Protection Agency
carries out a national program designed to evaluate population exposure to
ionizing and non-ionizing radiation, and to promote development of controls
necessary to protect the public health and safety. This literature survey was
undertaken to identify possible sources of ionizing radiation in the mineral
extraction industries (excluding uranium and phosphate). The information
gathered during the survey is also serving as a guide in planning further
studies to meet the requirements of the Clean Air Act (as amended in 1977).
Readers of this report are encouraged to inform the Office of Radiation
Programs of any omissions or errors. Comments or requests for further
information are also invited.
Donald W. Hendricks
Director, Office of
Radiation Programs, LVF
2.2.
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ABSTRACT
The mining, milling, and processing of mineral resources may cause varying
degrees of technologically enhanced natural radioactivity (TENR) which is de-
pendent on the inherent uranium and thorium content of the target resource and
the details of the total extraction process.
The objective of this review is to identify from the available domestic
literature possible metallic and nonmetallic mineral extraction industries
(exclusive of uranium, phosphate, and fossil fuels) which may require sub-
sequent assessment. Certain industries such as phosphate and coal are already
identified as potential sources of radioactivity; hence, they are excluded
from this overview.
Uranium and thorium content is a useful first order measure of the
radioactivity a mineral commodity may contain. This, in turn, is dependent on
the gross geochemical characteristics and geological history of the ore body
of concern. The observed variability of uranium and thorium content is de-
pendent not only on mineral genesis but also on the local geological setting.
This along with the absence of many direct observations prevents confident
selection of mineral commodities with consistently large TENR. However, the
following metallic commodities should be subject to further exploratory
inspection: rare-earth elements, gold, iron, molybdenum, copper, aluminum,
and lead-zinc. Among these, mining and milling of molybdenum and gold ores
have been associated with the largest radiation levels in air and water, re-
spectively. Placer deposits of any metal should be inspected for radiation
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related to the thorium decay chain. Similarly, resources which are the
residual results of weathering should be evaluated. Nonmetal resources which
appear to have the greatest potential of TENR are fluorspar, granite, and
clays. Underground operations in most any material may have elevated
radioactivity as is the case for caves in limestone, which consistently is
among the rocks having the lowest associated radioactivity. Radiation surveys
should involve the uranium and thorium decay chains and other naturally
occurring radioisotopes as applicable. Secondly, each operation should be
surveyed, restricting generalizations to the same geological province and to
deposits with similar local geology, mineralogy, and genesis.
IV
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TABLE OF CONTENTS
Paqe
PREFACE ii
ABSTRACT iii
LIST OF TABLES vii
ACKNOWLEDGMENTS viii
INTRODUCTION 1
GEOCHEMISTRY OF URANIUM AND THORIUM 4
Introduction 4
Igneous Rocks 6
Residual Igneous Rocks 8
URANIUM MINERALS IN METALLIC ORE DEPOSITS 11
Summary 16
WEATHERING AND SEDIMENTARY CYCLE 17
Introduction 17
Resistate Deposits 18
Residual Deposits 21
Organic Matter Associations 21
MINERAL EXTRACTION AND RADIOACTIVE BYPRODUCTS 23
RADIOACTIVITY MEASUREMENTS ASSOCIATED WITH
MINING OPERATIONS 25
SUMMARY 31
Conclusions 31
Recommendations 33
REFERENCES 35
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APPENDICES
A. Radiological Data for Selected
Metallic Commodities 42
B. Radiological Data for Selected
Nonmetallic Commodities 45
C. Glossary of Geological Terms Used 46
TABLES 50
vi
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LIST OF TABLES
Number Page
1 Uranium and Thorium Content of Minerals 50
Found in Igneous Rocks
2 Generalized Distributions of Uranium in 50
Various Groups of Igneous Rocks
3 Uranium and Thorium Content of Selected 51
Sedimentary Rocks
4 Summary of Radiological Information on 52
Metallic Commodities Given in Appendix A
5 Summary of Radiological Information on 53
Nonmetallic Commodities Given in Appendix B
Vll
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ACKNOWLEDGMENTS
I wish to thank the staff of the Office of Radiation Programs-Las Vegas
Facility for their assistance, criticisms, and suggestions during the
preparation of this report. I am appreciative of the help provided by C.
Robbins, Office of Radiation Programs-Headquarters; R. Rock, Mining and Safety
Administration (now Mining Safety and Health Administration); A. Goodwin,
Mining Safety and Health Administration, in supplying technical information;
and to A. Tanner and J. Stuckless of the U. S. Geological Survey and R.
Kaufmann, ORP-LVF, for taking the time to review this report and for providing
numerous criticisms and suggestions. A special thanks to Mr. David Ball for
his graphic and artistic contribution particularly in preparation of the cover
illustration and to Mrs. Edith Boyd and Ms. Sandi Graves for assisting in the
typing.
Vlll
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INTRODUCTION
In order to establish radiation protection guidance, the Office of Radia-
tion Programs (ORP) of the U. S. Environmental Protection Agency (USEPA) makes
a continuing effort to identify source categories of radiation. An area of
increasing interest involves the identification of enhanced human exposure to
ambient radiation and radioactive material resulting from various human
activities that concentrate or redistribute radioactive material in the
earth's crust.
This brief review is intended as an overview document which will support
ORP efforts under the Clean Air Act as amended in 1977. This review is not to
be considered inclusive and primarily will address readily available domestic
literature only. Secondly, a substantial amount of current information
germane to this report on uranium and thorium concentrations in various
geological materials is unpublished. Some of the observations given herein are
admittedly dated but are included for lack of more recent information. This
report primarily provides some background information on which further
investigative activities can be based.
Of the approximately one hundred naturally occurring radionuclides, about
thirty (most of which are members of the uranium and thorium decay series) are
of interest due to their abundance and toxicity (Conference of Radiation
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Control Program Directors, 1977). Natural radiation is by far the largest
source of human radiation exposure to the world population (United Nations
Scientific Committee on the Effects of Atomic Radiation, 1977). The major
portion of this exposure is unavoidable. However, as a result of industrial
activities and changes in modes of living due to technological advances,
increased exposures to naturally occurring radioactive materials can take
place. This process has been designated as "Technologically Enhanced Natural
Radiation" or TENR (Gesell and Prichard, 1975).
Extraction and processing of mineral commodities may enhance exposure of
humans to natural radioactivity in several ways. Workers located in or adja-
cent to mining sites can be exposed to gamma radiation from the ore body as
well as the surrounding rocks. Exhalation of radon gas from exposed surfaces
can result in an inhalation hazard to mine workers, particularly in under-
ground operations. Beneficiation, involving such operations as grinding,
washing, flotation, drying, or chemical extraction, can redistribute or con-
centrate radioactive material in tailings, byproducts, products, or wastes.
Tailings may become a hazard if used in construction or reclamation. Waste
water may contaminate surface water or find its way into ground water. Pot-
able water supplies may be contaminated and result in radiation exposure to
users. If radioisotopes are concentrated in a product or byproduct, exposure
can result when this material is fabricated into a consumer product and ul-
timately located in close proximity to humans in either the home or work
place. However, this facet is not within the scope of the study presented
herein.
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Occupational and public radiation exposures as a result of uranium mining
and milling have been documented and were initially investigated in this coun-
try in the early 1950's. Studies of radiation exposure associated with cer-
tain phosphate mining and processing operations have been conducted by Spal-
ding (1972), Guimond and Windham (1975), and the U. S. Environmental Prot-
ection Agency (1973). In many respects, exposure to elevated levels of
radioactivity as a result of phosphate extraction has occurred in a manner
similar to that from uranium extraction. Exposure can occur via inhalation of
radon gas and its radioactive decay products in enclosed areas (USEPA, 1975),
direct exposure to gamma radiation from solid waste and byproduct material
(Duncan et al., 1977), and ingestion of water from supplies which have ele-
vated radioactivity (Kaufmann and Bliss, 1977).
These and other findings have led to this attempt to identify potential
sources of radiation exposure resulting from mineral commodity extraction and
production operations. As a first step, the present study attempts to indi-
cate, through an examination of the domestic literature, those minerals which
may be expected to be associated with increased concentrations of naturally
occurring radioactivity. Emphasis is on resource development (mining, proces-
sing) rather than on product or byproduct use by the consumer.
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GEOCHEMISTRY OF URANIUM AND THORIUM
INTRODUCTION
The movement of uranium, thorium, and associated elements in the earth is
part of a natural geochemical cycle between rock, water, and air. While human
dose assessment is one of the ultimate concerns, the understanding of the
enrichment processes of radioactive elements in the lithosphere has direct
application in defining extractive mineral ore bodies which may show
preferential enrichment in radioactivity.
The behavior of uranium and thorium is dependent on the outer electron
configuration. For example, thorium is analogous to the rare-earth elements,
with an incomplete 5f shell. A valence state of 4+ is dominant with 3+ or
2+ states occasionally noted. Only the tetravalent state is observed for
thorium under natural surface conditions. In general, thorium compounds
exhibit low solubility. The thorium ion in solution is small, highly-charged,
and forms an extensive number of complexes (Ames and Rai, 1978). In the
tetravalent state the ionic radius is similar to U+ and Ce+.
Uranium has been identified as forming about 103 distinct minerals.
Uraninite is the most commonly identified ore mineral. Many secondary
minerals can be formed including sulfates, silicates, phosphates, molybdates,
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and vanadates as well as multiple oxides (Ames and Rai, 1978). Generally, the
geochemistry of uranium is intimately associated with thorium, particularly in
the distribution in igneous rocks. However, significant separation between
the two elements does occur during weathering, transport, and deposition in
the sedimentary cycle (Rogers and Adams, 1969b).
The overall similarity in size, electron configuration, and bonding nature
of thorium, cerium, uranium, and zirconium promotes geochemical association
with various other elements (Bayer, 1974). These associations provide
valuable keys to defining possible ores and products or byproducts wherein
there is enrichment of radioactive elements. Many observed elemental
assemblages can be predicted by noting similarity in outer electron
configurations and other relevant properties as noted above.
Two broad processes whereby radioactive elements relate to the geochemical
cycle include igneous differentiation and sedimentary deposition. Both
processes can cause reconcentration of radioactive elements. For igneous
rocks, differentiation by fractional crystallization of magma is one of the
primary processes for partitioning elements. Certain late crystallizing
minerals, e.g., potassium and sodium feldspars and quartz, may be enriched in
trace elements (including uranium and thorium) due in part to their increased
concentration in the magma from which these minerals crystallize. Secondly,
gases and fluids expelled from cooling magmas are thought to be responsible
for the formation of many metallic ore deposits, particularly those of
hydrothermal origin. Occasionally, surface or ground water remobilizes
uranium and other metals and redeposits them as secondary minerals or
secondary ore deposits. Other concentrating mechanisms occur in the
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sedimentary cycle and particularly involve minerals containing thorium. Many
of these minerals are resistates, i.e., minerals resistant to chemical and
physical weathering, as well as being characterized by high specific gravity.
Because of these properties, thorium minerals, when introduced into dynamic
water bodies, may form placer deposits. Another site of enrichment involves
the concentration of uranium by organic or organically derived material. This
accounts for the association of uranium with humates, coal (particularly
lignites), oil, and peat.
IGNEOUS ROCKS
While uranium and thorium are observed in all major rock forming minerals
(Table 1), the mechanics of location within the mineral are largely unknown.
Generally, the mafic minerals, i.e., those enriched in magnesium and iron, are
also enriched in uranium and thorium; but there are many exceptions.
Accessory minerals, i.e., minerals occurring in small quantities in a rock,
are usually greatly enriched in uranium and thorium, particularly in granites.
Accessory minerals particularly enriched in thorium are allanite and monazite.
Xenotime is enriched in uranium. The common accessory minerals, zircon and
sphene, generally have a low Th/U ratio of 1 to 2 which may be either an
expression of early magmatic composition or differential enrichment of uranium
(Rogers and Adams, 1969a). The St. Francois Mountains of Missouri are noted
as being enriched in uranium (10 to 30 ppm) and investigation of its
petrography by Mash (1977, p. 30) revealed that 80 percent of the uranium is
located as rims about magnetite crystals. Lesser amounts are associated with
the biotite. Stuckless et a!., (1977) noted similar patterns in magnetite
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crystals at Granite Mountain, Wyoming. The biotitic phase is particularly
enriched in uranium. They calculate an average uranium concentration of
9.8 ppm but if suggested levels of uranium loss are correct, the rock may have
contained an average of as much as 30 ppm uranium. The content is highest in
the accessory minerals zircon, sphene, and monazite with lesser amounts in
epidotes, apatites and biotitic/chloritic alteration products (Stuckless et
al., 1977). They also noted that uranium was not obvious in either inter-
granular borders or in fractures.
Before making generalizations on igneous rocks, it should be noted that
some geographic areas have an overall elevated concentration of uranium and
thorium regardless of rock type or geological age. Such areas include the
Rocky Mountain Front (Phair and Gottfried, 1964) in Colorado and part of New
England (Rogers and Adams, 1969a). Portions of central Wyoming as well as
parts of the Colorado Plateau may also fall into this category (Stuckless,
written communication, 1978). Putting such geographic variability aside, ura-
nium content increases as the silica content increases. This property is the
result of uranium exclusion from early minerals and rocks formed in the
processes of magmatic differentiation. Whether intrusive or extrusive, ig-
neous rocks tend to show similarity in uranium and silica distribution. While
individual rock suites commonly exhibit uranium enrichment in later members,
it is not universal (Rogers and Adams, 1969a). Thorium generally exhibits the
same geochemical trends in petrological evolution as uranium (Rogers and
Adams, 1969b). Thorium is also closely tied to potassium with a K/Th ratio
"nearly constant...in a large variety of igneous rocks" (Heier and Rogers,
1963).
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RESIDUAL IGNEOUS ROCKS
Pegmatites, possibly the last residual portion of a magma to crystallize,
often move some distance from the parent magma. Enriched in a wide range of
elements not easily incorporated into common minerals of the cooling magma,
pegmatites have been used as a source of many rare metals including lithium,
beryllium, scandium, rubidium, yttrium, zirconium, molybdenum, tin, cesium;
the rare-earth elements, columbium (niobium), tantalum, tungsten, thorium, and
uranium. Industrial minerals produced from pegmatites include feldspar,
muscovite, phlogopite, tourmaline, and quartz (Mason, 1966; Bates, 1960).
Pegmatites are a complex group of rocks containing diverse mineralogical
and compositional members. The largest pegmatite mines and the only ones
which have operated on a more or less continuous basis are those extracting
feldspar (Bates, 1960). Mica, spodumene, and beryl are often important by-
products. Production is greatest in North Carolina with substantial produc-
tion also in California, South Dakota, and Colorado. Usually, domestic
pegmatites are not considered a commercial source of uranium and thorium.
However, pegmatites having significant amounts of uranium stimulated some
interest in the past (Lang, 1952; Page, 1950) and Charbonneau and Jonasson
(1975) more recently referred to "radioactive pegmatites" in Ontario.
Garside (1973) indicates that uranium, thorium, and rare-earth minerals are
common accessory minerals in pegmatites. He noted 33 so-called radioactive
pegmatites occur in Nevada. Similar occurrences of radioactive minerals were
observed in pegmatites around Kingman, Arizona (Peirce et al., 1970).
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Uranium content appears to be strongly related to potash feldspar content
of the pegmatites (Page, 1950). This appears to be a logical continuation of
the geochemical behavior of uranium and potassium as observed in common ig-
neous rocks. Radioactivity in pegmatites can have a broad regional impact.
DalTAglio (1971) examined the uranium content of water in the Italian Alpine
range and found anomalous areas. Subsequent radiometric surveys revealed that
the source was pegmatites which contain 3 to 10 times the background uranium
content.
Carbonatites are particularly enriched in a wide range of elements
including rare-earth elements (lanthanides and yttrium). Deposits at Mountain
Pass, California, constitute a major reserve of these materials. This deposit
also contains the thorium minerals thorite and bastnaesite and less frequently
monazite and allanite (Staatz, 1974). The vein was initially investigated as
a result of elevated radioactivity. Nininger (1955) noted that thorium is
found in a number of rare-earth minerals and identified Mountain Pass among 13
important thorium-bearing vein deposits in the United States. Association of
rare-earth elements, uranium, and thorium has been observed in vein deposits
in the Bokan Mountains of Alaska. Geological investigations by M. H. Staatz
(1977) revealed that some of these veins are traceable for about 2.8 km and
that uranium content varies from 0.005 to 2.8 percent while rare-earth
elements and thorium concentrations vary between a few hundredths of a percent
to over 10 percent. Enrichment of barium, beryllum, niobium, strontium, and
zirconium has also been noted in these deposits. Because of the common
associations of rare-earths and thorium, extraction of one could involve the
extraction of the other as a byproduct or possible enrichment in the
processing of wastes.
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While of minor importance, another radiation source may be from several
rare-earth elements which have radioisotopes including lanthanum-138,
neodymium-144, samarium-147, and lutetium-176 (Lowder and Solon, 1956).
In summary, residual rocks like pegmatites may be enriched in uranium and
thorium, particularly if the potassium content is high. Carbonatites with
substantial rare-earth content appear to be somewhat radioactive.
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URANIUM MINERALS IN METALLIC ORE DEPOSITS
Two approaches can be taken in analyzing uranium distribution in mineral
deposits. One is to observe associations in uranium ore deposits. This can
help to define geochemical affinities which may be applicable to other types
of commodities and ore deposits. The second is to observe uranium minerals
which occur in other types of ore deposits and thereby define potential
radioactive hazards in other mineral extraction operations.
Many major metallic deposits are believed to have been generated by gases
and liquids moving away from cooling magmas. Deposition of minerals from
these fluids involves complex processes with definite geochemical associations
among resulting mineral and element assemblages. In examining uranium ore
deposits, several classifications have been developed based upon persistent
mineralogical and chemical associations. McKelvey (1955) classified uranium
vein deposits into three principal mineral groups: (1) nickel-cobalt-native
silver-pitchblende, (2) pyrite-galena-pitchblende, and (3) uraniferous
fluorite veins. Everhart (1956) also identified three types of deposits: (1)
siliceous-pyrite-galena (a type of major importance), (2) nickel-cobalt-native
silver, and (3) gold bearing pyrite. Everhart and Wright (1953) noted that
epigenetic uranium deposits are more likely in veins containing either a)
cobalt, nickel, and silver or b) copper, lead, zinc, and silver.
Direct mineral associations with uranium deposits may occur within the ore
body or on a regional basis. In the Coeur d'Alene mining district, uranium
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deposits are spatially associated with silver and base metal ores but exact
genetic association is uncertain (Butler and Schnabel, 1956). Uranium de-
posits occur as part of the metal assemblage of ore deposits in the central
mineral belt of Colorado (King et al., 1953), whereas those in the Front Range
of Colorado are usually associated with molybdenum. Within this province,
molybdenum is used as a geochemical indicator of possible uranium deposits
(Ferris and Bennett, 1977). A similar relationship has been observed in the
Marysvale, Utah, district (McKelvey et al., 1955).
McKelvey et al. (1955) noted that the list of metallic minerals found with
uranium vein deposits is extensive. In their judgment, iron minerals are the
most "nearly universal and conspicuous" association. The iron mineral may be
pyrite or marcasite but finely dispersed hematite is considered to be poten-
tially indicative of uraninite association. Magnetite is found associated
with pitchblende at Maryvale, Utah, whereas some magnetite deposits in New
Jersey and New York have trace amounts of uraninite. In general, "...large
magnetite iron ore bodies of the world are not abnormally radioactive"
(McKelvey et al., 1955).
The second most common metallic element associated with uranium deposits
is copper. Most common copper minerals have been observed with uraninite ore
types. Uranium minerals are also commonly associated with those containing
cobalt which is an important geochemical indicator, particularly for the
Ni-Co-Ag uranium ore type (McKelvey et al., 1955).
Lead is the next metal in abundance in uranium deposits. Galena is the
principle mineral observed, but "...lead-bearing veins are singularly
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nonradioactive" (McKelvey et al., 1955). After lead in abundance is nickel
which, when associated with uranium, is generally restricted to
cobalt-nickel-silver ore types. Nickel deposits not characterized by the
cobalt-silver association are not usually observed to be particularly radioac-
tive.
Minerals containing silver tend to coexist with uraniferous veins but are
zoned in such a fashion that the association is more regional than local.
Although zinc is also found in uraniferous veins, "...many rich zinc ores
throughout the world are nonradioactive" (McKelvey et al., 1955).
Other metal lies of note are molybdenum, native bismuth, titanium, and
vanadium. Molybdenum minerals are observed in the Marysvale district, Utah
and in other mining districts. Occurrence is more likely in the Si-Fe-Pb ore
type. Native bismuth is generally restricted to the Co-Ni-Ag ore type.
Bismuth ores tend to be slightly radioactive. Titanium occurrence is
localized and tends to occur together with uranium in the same mineral,
davidite. Vanadium is sporadically present and most common in low temperature
uranium deposits. Carnotite, a potassium-uranium vanadate, is the most
common mineral (McKelvey et al., 1955).
Uranium minerals have been observed in a variety of hydrothermal metallic
ore deposits. Butler and Schnabel (1955) indicated that uranium was found
associated with base metal sulfides and precious metals in several western
states and Michigan. Usually reserves of uranium are low, typically less than
1000 tons of uranium ore (of unspecified grade). Traces of uranium have been
found with gold and zinc minerals (Leonard, 1952). Investigation of mercury
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deposits in the McDermitt caldera in Nevada-Oregon by Rytuba (1977) revealed
that associated opalitic material contained up to 520 ppm uranium.
Uranium is also observed in iron formations. Everhart (1956) noted that
uraninite is associated with various iron minerals in the iron-bearing strata
and quartzite of upper Huronian age metasediments in Michigan. Uranium in
iron formations is often associated with copper, lead, and zinc (Butler and
Schnabel, 1956). While uranium may occur with iron minerals, thorium has been
observed as detrital grains of monazite in the associated metasediments as ob-
served in rock dumps of abandoned iron mines in Marquette County, Michigan
(Vickers, 1956). The Old Bed Mine, a magnetite deposit near Mineville, New
York, has thin seams of fluorapatite "usually rich in thorium and rare-
earths." Similar type deposits exist elsewhere in the area (Twenhofel and
Buck, 1956).
Uranium minerals in the Camp Smith area of New York occur in a complex
sequence of Precambrian metamorphic rocks. Uraninite occurs in association
with several lithologies as well as with a massive strata-bound Cu-Ni ore body
(Grauch and Campbell, 1977). Popenoe (1966) noted that a major aero-
radioactivity anomaly was associated with a mine positioned on the
sulfide ore body.
The strongest association of uranium with gold tends to occur in
metasediments, particularly conglomerates. Vein deposit associations are
infrequent but have been observed in the Front Range of Colorado.
Metasediment deposits include the Missisagi Conglomerate of the Blind River
District, Ontario and the Witwatersrand Conglomerates in South Africa.
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The occurrence of uraninite in the Witwatersrand gold deposits of Precambrian
age was first noted by Cooper (1923). Subsequently it was determined that a
frequently observed ore component referred to as "carbon" was an
uraninite-carbon aggregate (Davidson and Bowie, 1951). The average ore grade
in terms of uranium is approximately 0.03 percent. Generally, mine operators
considered gold to be enriched when "carbon" occurred in greater amounts (Park
and MacDiarmid, 1970). Substantial uranium has been recovered as part of gold
processing in South Africa beginning near the conclusion of World War II.
Uranium, in fact, has become more important than gold production in some parts
of the Witwatersrand district (Nuclear Fuel, 1977b). In some cases, defunct
gold mines are being re-evaluated in terms of potential uranium production
(Nuclear Fuel, 1977a).
Uranium minerals have been observed in a variety of fluorite deposits.
Brown et al. (1954) noted that uranium minerals occur in fluorite deposits in
Illinois, and Wilmart et al. (1952) observed that in the Rocky Mountain area
uranium can either be disseminated as discrete mineral grains or contained
within the host mineral of the fluorite ore bodies. Secondary uranium mineral
coating in fractures and vugs in both fluorite ore bodies and adjacent wall
rock was also recorded. Butler and Schnabel (1956) noted that 20 fluorite
deposits or "fluorite-bearing ores" had noticeable uranium.
From a broader geochemical viewpoint, Van Alstine and Shawe (1976) ob-
served that fluorine has a tendency to be associated with beryllium, man-
ganese, columbium (niobium), tin, tungsten, uranium, yttrium, lead, and zinc.
McKelvey et al. (1955) noted that fluorite is a persistent, but minor,
constituent of a majority of uranium vein deposits. While uranium is
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associated with fluorspar deposits in the western United States, deposits in
the central and eastern United States, outside of the Illinois-Kentucky
district, exhibit thorium minerals as a possible associated constituent (Heyl
and Van Alstine, 1976). It would appear that fluorspar may exhibit
radioactivity either from the uranium series or thorium series. Griffitts and
Van Alstine (1976) suggest that radioactivity may be a useful tool for
exploration of fluorspar-uranium deposits similar to those seen in the Thomas
Range, Utah, which contains "the largest known uraniferous fluorspar deposit
in the United States" (Staatz and Osterwald, 1956). The extreme case of
uranium mineral association with fluorite is the Marysvale, Utah ore body
which is an important source of uranium. Currently, exploration for uranium
has been planned for fluorspar claims in Utah {Engineering Mining Journal,
1978; p. 149).
SUMMARY
In summary, uranium ore deposits are associated with a wide variety of
metallic and nonmetallic elements. In vein deposits, McKelvey (1955) ranked
the following metallic elements found with uranium vein deposits (in de-
scending order of uranium abundance): iron, copper, cobalt, lead, nickel,
silver, zinc. Gold is occasionally noted. Important nonmetallic elements
include silica and fluorine. Precambrian iron and magnetite deposits on the
U.S. east coast contain uranium minerals. Gold and uranium are observed in
metasediments. Fluorite deposits can contain either uranium or thorium
minerals.
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WEATHERING AND SEDIMENTARY CYCLE
INTRODUCTION
It is during weathering and the sedimentary cycle that major separation
occurs between uranium and thorium. This is due in part because uranium
oxidizes to a relatively soluble uranyl ion compared to the thorium form.
Uranium deposition is occasionally difficult to explain due in part to the ob-
vious absence of reducing agents of any sort to act on the uranyl ion.
Krauskopf (1976) suggests that under conditions of alkalinity and carbonate
ion availability, highly soluble uranium carbonate complexes may form and con-
tribute to uranium mobility. Experimentation conducted by Naumov and Mironova
(1969) substantiate this suggestion as well as showing that carbonate com-
plexes may also play a role in uranium mobility even with temperatures in the
range of 100 to 200°C. Uranium deposits appear to be related to reduction in
carbonate content by either carbon dioxide degassing or wall rock inter-
action.
When rocks are subject to weathering, thorium either remains tied up in
resistate minerals or is "...strongly adsorbed by clay particles or present as
insoluble oxides and hydroxides" (Ames and Rai, 1978). Thorium resistance
to chemical mobility is well exhibited in extremely weathered soils.
Bauxites, which are one end product of intense weathering, may have thorium
concentrations up to 50 ppm or more (Adams and Richardson, 1960). In summary,
uranium is moved into the environment of sedimentary deposition in solution;
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thorium is moved into the depositional environment associated with discrete
grains. This fundamental behavioral difference effectively decouples the two
elements (Table 3).
RESISTATE DEPOSITS
In igneous rocks, trace minerals bearing significant amounts of thorium
are usually resistant to surface and near surface chemical weathering proces-
ses. Such minerals will largely be mobilized only when the grains are phys-
ically transported in a high energy environment typified by fluvial and/or
beach settings. Due to their higher specific gravity than the associated
quartz and clay particles, these mineral grains may become concentrated. Such
deposits have been subject to extensive study, particularly in Brazil (Roser
et al., 1964; Penna-Franca, 1975). Some of these beach deposits are utilized
as a source of thorium. Other mineral resources (e.g. rutile) concentrated by
similar processes may also contain substantial concentrations of radioactive
resistates.
Placer deposits generated by streams and rivers as well as by shoreline
processes could contain a variety of deposits of economic importance including
gold, platinum, and inert oxides and silicates of zirconium, tin, chrome,
tungsten, and titanium (Park and MacDiarmid, 1970). The radiation hazard, if
any, from such deposits is dependent on the geology of the source area, posi-
tioning of the deposit relative to the land surface, and a host of variables
relating to land and water use by man or segments of the human food chain.
18
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Because of elevated radioactivity, placer deposits along streams in Idaho
have been investigated. Mackin and Schmidt (1956) concluded that most of the
radioactive minerals found in the placer was derived from quartz monzonite, a
component of the Idaho batholith. The placers in Bear Valley are particularly
enriched with these minerals. In some areas, monazite, and euxenite occur in
the ratio (by weight) of about 1:2 with approximately 0.5 pounds monazite per
cubic yard (Mackin and Schmidt, 1956). During the interval of 1955 to 1960 a
plant 20 miles to the south at Lowman, Idaho processed about 200,000 tons of
placer material from Bear Valley. Minerals extracted include columbite,
euxenite, monazite, magnetite, ilmenite, zircon, and garnet. Subsequent
inspection of the plant site was made to assess potential radiation hazard
(Ford, Bacon, and Davis, Inc., 1977). While thorium is an obvious portion of
the ore mineralogy, no attempt was made to quantify the potential radiation
hazard from the thorium-232 decay scheme. The uranium-238 decay chain was ad-
dressed, however.
Placers of various ages may contain thorium. Twenhofel and Buck (1956)
observed Precambrian age quartzites which contain thorium minerals. Previous
discussion touched on the fact that detrital grains of monazite in metasedi-
ment of possible placer origin are adjacent stratigraphically to Precambrian
age iron formation. The Witwatersrand gold deposit is accepted by some as a
placer deposit. Overall, gold placer deposits have been the subject of ex-
tensive exploitation. There also has been substantial interest in titanium
deposits in eastern Florida beach deposits (Lynd, 1960; Park and MacDiarmid,
1970). The two principal deposits are located at Trail Ridge and east of
Jacksonville with monazite being identified among the mineral assemblage of
the former. Numerous occurrences of titaniferous sands are common in Florida
19
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but are usually less than commercial grade. Sand sampled from Venice Beach
was found to contain between 0.05 and 1.5 percent monazite (Florida Department
of Health and Rehabilitative Services, 1976). In general, Florida "black"
sand contains 250 to 1000 ppm thorium with an average of 300 ppm and about an
order of magnitude less uranium (Osmond, 1964).
Processing of heavy sands has created some radioactivity problems. In
Albany, Oregon there has been extensive processing of zirconium as well as
other rare metals including columbium, tantalum, and hafnium (Boly, 1977).
Ore of these metals usually contains substantial radioactivity, which in the
Wan Chang operation is concentrated in a "flour-like mineral residual" which
is radioactive. Leachate water associated with wastes buried on the plant
site contained on the order of 45,000 pCi/1 of radium-226 (State of Oregon
Health Division as cited in Boly, 1977). Approximately 4000 tons of this
waste material are located at the plant site with similar material disposed of
at several locations outside the plant site, including the Coffin Butte
landfill near Adair Village.
In summary, placer deposits of any type have a potential for elevated
radioactivity during mineral extraction and processing. The thorium-232 decay
series is especially, but not exclusively, the source of activity.
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RESIDUAL DEPOSITS
While soil can be expected to reflect some properties inherited from the
underlying bedrock, significant deviations are observed in radioactivity
levels between the two. Soils are the result of complex chemical, biological,
and physical processes which alter the concentration of certain elements.
This is particularly true when conditions involve extensive, long-term chemi-
cal weathering and minimal physical transport. For example, Pinkerton et al.
(1964) found that the soil over limestone in Maryland was quite radioactive
despite the low activity of limestone. This is due in part to selected con-
centrations of radioactive elements in the parent rock as it weathers into
soil. Bauxites, the principal aluminum ore, are complex aggregates of iron
and aluminum minerals which form as residual deposits, often over limestone,
under tropical climatic conditions (Park and MacDiarmid, 1970). They have
been observed to have substantially higher levels of uranium and thorium
(Polanski, 1965) than the parent limestone (Table 3). Although not signific-
ant in the continental United States, important residual ores include man-
ganese oxides in India and nickel in New Caledonia (Park and MacDiarmid,
1970).
ORGANIC MATTER ASSOCIATIONS
While it is beyond the scope of this report to detail the relationships,
organic matter can play an important role in uranium deposition. Much of the
radioactivity in sedimentary rocks is found to be related to organic residues.
Breger and Deul (1956) note that the close association between carbonaceous
21
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material and uranium may be the result of three mechanisms: (1) organic
matter acts directly as a reducing agent converting the soluble uranyl complex
to insoluble uranous ion, (2) sulfide ubiquitously present in organic debris
acts as the reducing agent and, (3) the carbonaceous material acts as a
chemical precipitant in some unknown fashion. Jennings and Leventhal (1977)
proposed a structural model of humic-acid type material which identifies sites
for uranium attachment.
Organic materials which can exhibit substantial uranium enrichment include
coal (esp. lignite), humate, black shale, asphalt, and oil. Armstrong and
Heemstra (1973) noted that as oil becomes more oxidized or asphaltic, total
uranium content increases. Rocks with unusually high levels of organic
residue or asphalt-bearing rocks also tend to exhibit higher levels of
radioactivity. Hail et al., (1956) found that ash of the extracted oil con-
tained from 0.028 to 0.376 percent uranium. Uranium is clearly confined to
the organic fraction of material and not in the confining rock. Uranium is
enriched in lignite, particularly in deposits in the upper Great Plains (Vine,
1956). Denson et al. (1960) analysed 275 surface and 1000 core samples and
found uranium content to vary between 0.005 and 0.02 percent.
Living organic matter may even have a more active role in uranium
deposition. Jensen (1958) suggests that anaerobic bacteria may act as a
source of hydrogen sulfide which in turn promotes uranium precipitation.
In summary, organic matter is an important agent which can concentrate
uranium in the sedimentary cycle. In contrast, thorium is enhanced in
residual or resistate deposits such as placers and soil.
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MINERAL EXTRACTION AND RADIOACTIVE BYPRODUCTS
A specific mining operation may involve elevated (relative to background)
radioactivity if the principal ore material contains or is associated with
uranium and/or thorium and their daughters. Obviously, the potential for a
radiological health hazard depends on whether significant amounts of
radionuclides are present and benefaction results in sufficient radioactivity
to be of concern in the product, waste, or environs. Radioactivity levels so
created may increase occupational and/or general population exposure. The
occurrence of radioactivity in byproducts is also cause for concern. In
certain instances, uranium is, or soon will be, recovered as a byproduct of
phosphate, copper, and gold extraction. For example, the Central Florida
Land-Pebble Phosphate District was initially identified as having significant
amounts of uranium (Cathcart, 1963a; 1963b; 1963c; 1964; 1966) yet large scale
byproduct extraction during phosphate processing only began in late 1975
(Finch, 1977). The potential radiological hazard posed by phosphate mining
and processing has only recently been evaluated, partly in response to
increased local population and competition for land and water.
Byproduct production of uranium is being implemented as part of copper
extraction in Utah. Another operation proposed in Utah involves extraction of
uranium from beryllium ore (Engineering and Mining Journal, 1978; p. 149). In
the Witwatersrand district of South Africa, uranium minerals were reported as
part of the ore mineralogy as early as 1923 (Cooper, 1923). However, by-
product recovery of uranium was not attempted until the latter part of World
23
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War II. In some cases uranium has become the principal metal of economic
interest. As the demand for uranium increases, other mining industries are
likely to become potential sources of uranium or thorium. As these new
resource materials are identified, a need will develop to identify potential
radioactivity problems they may pose.
In summary, uranium byproduct extraction has been made in phosphate,
copper, and gold ore processing. Similar extraction operations have been
suggested for beryllium ore in Utah.
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RADIOACTIVITY MEASUREMENTS ASSOCIATED WITH MINING OPERATIONS
A limited amount of information concerning radiation and ratiation dose is
available in and adjacent to non-uranium mining operations. Included in this
category is information defining trace concentrations of uranium and thorium
in ore bodies and surrounding terrain. The Mine Safety and Health Administra-
tion (MSHA) is the principal Federal Agency concerned with radiation levels in
underground mine air and the principal source of the information presented
herein (Rock, 1977, written communications; Goodwin, 1978, written
communications). Radioactivity measurements made to date in mines are
primarily concerned with the assessment of potential hazard to miners and may
not or may only indirectly relate to ore geochemistry. Radon in some mines
has been attributed to sources other than the ore, as in the case at the Pine
Creek tungsten mine, California where ground water is believed to be the radon
source (Rock, 1977, written communication). Secondly, the presence or
absence of ventilation may play an important role in mine air radioactivity.
Clearly, an underground operation which for a variety of reasons has excellent
ventilation can have low concentrations of airborne radioactivity but a high
overall radioactivity potential. Procedural variability in atmospheric radia-
tion measurements made by MSHA is also present (Andrews, personal com-
munication, 1978). In general the available data are very limited and vary
from qualitative to quantitative. It includes observations from both water
and air measurements. It is unknown how representative these numbers are. It
is also unknown how the available observations on activity levels relate to
water and air outside the mine or how they interrelate to other possible
25
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radiological source terms of the mining operation. Radium-226 levels in mine
related water are expressed as picocuries per liter (pCi/1). For the purposes
of this report they are compared to the 5 pCi/1 limit of radium-226 plus
radium-228 set by the national interim primary water regulations (USEPA,
1976). Selected ores or mines will be noted if radon/radon daughters are
thought to be elevated (subjective experience of Rock, personal communication,
1977) but exact values are not available. Otherwise, radon/radon daughters
are expressed as working levels (WL). All the quantitative data from MSHA
were taken from a list of observations of 0.1 WL or greater. Therefore, they
may not be typical of the vast majority of operations in a given mineral
industry. (A WL is defined as any combination of short lived radon daughters
in 1 liter of air which will produce 1.3 x 10^ million electron volts of
potential alpha energy.) MSHA regulations require corrective action when mine
atmosphere levels exceed 1.0 WL.
Substantial effort has been made to investigate radioactivity associated
with ore bodies. In part, this is to determine whether radioactivity may be
helpful in exploration and ore definition. Gross (1952) inspected gold mines
located in igneous stocks in Canada and found that elevated radioactivity was
a pervasive feature. Moxham et al. (1965) observed that uranium was enriched
about four times that of the surrounding country rock in tiie Bagdad Copper
Mine, Arizona. However Moxham et al. (1965) also conducted radiation surveys
of three Precambrian age massive sulfide deposits in North-Central Arizona:
1) United Verde/United Verde Extension Mine at Jerome, a massive copper-zinc
deposit; 2) Iron King Mine, a massive lead-zinc deposit; 3) Old Dick Mine near
Bagdad, a massive copper-zinc mine. No significant systematic dependency was
observed between uranium or thorium content in either the alteration or
26
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mineralized configuration of any of the mines. Gangadharam et al. (1963)
similarly noted that the copper and uranium content were essentially
independent in the environment of a massive sulfide ore body at the Mosaboni
Copper Mine, India.
Fitzgerald (1976) reviewed the literature concerning radioactivity
associated with low grade copper deposits. One of the principal contributors
he notes is Still (1962) who observed the uranium content of various porphyry
copper deposits in the Miami District of Arizona. The geometric mean of 140
observations by Still (as given by Fitzgerald, 1976) at the Copper City Mine
is about 50 ppm uranium. A second mine in the district, the Castle Dome, had
a geometric mean of approximately 10 ppm. Apparently within the same mining
district, the uranium content of similar ore body types may vary considerably.
The enrichment of potassium is a common feature of porphyry copper deposits
and attributed to a variety of processes (Davis and Guilbert, 1973).
Potassium-40 is a radioisotope which makes up about 0.01 percent of natural
potassium and may contribute to the overall radioactivity of an ore body
(Davis and Guilbert, 1973). They note that others in the area of theoretical
crystal chemistry have suggested that uranium as well as thorium could also be
enriched along with potassium. However, investigation by Davis and Guilbert
(1973) of four porphyry copper mines and adjacent geologically similar
features without copper mineralization revealed that uranium and thorium are
not systematically enriched as a result of or in association with copper
mineralization. A weighted average uranium content from mineralized
occurrences is 0.95 ppm (Data taken from Table 1; Davis and Guilbert, 1973;
p. 157). For barren sites the weighted average uranium content is 0.63 ppm.
27
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Analysis by the U.S. Bureau of Mines of 4 copper, 1 molybdenum, and 5
lead-zinc tailing samples revealed less than 30 ppm 0303. One lead-zinc
tailing sample contained 60 ppm U^QQ and a phosphate tailing sample con-
tained 150 ppm 1)303 (written communication, K. Dean, U.S. Bureau of Mines
to R. Snelling, 1970). Addressing the problem from a mineralogical point of
view, trace amounts of uranium in pyrite, sphalerite, and galena have been
observed to vary from one to several thousand parts per million (Wright et
al., 1960). They suggest that in samples with greater than 80 ppm, uranium
appears to be irregularly distributed and, therefore, not strongly related to
the fluid which deposited the metal sulfide. Stuckless (written commu-
nication, 1978) suggests that this may even be true for concentrations even
greater than 8 ppm. Apparently trace amounts of uranium in sulfides are re-
lated to secondary processes or microcrystalline minerals not directly tied to
sulfide deposition. Secondly, uranium content appears to be dependent more on
regional availability than on mineral genesis.
Metallic commodities and associated radioactivity observations are
summarized in Table 4. Radium-226 data are taken from Supplement B-13,
radiological data, Calspan Corp. (1975) and air sampling data supplied by
MSHA. Working levels shown are derived from a list which notes underground
mines with at least one sample of 0.1 WL or greater. For commodities with
three or more maximum WL observations available, the rank from highest to
lowest is 1) molybdenum, 2) iron, 3) lead/zinc, and 4) gold. If all
commodities are pooled, the average maximum WL is 0.54. Only molybdenum is
greater (0.83) in terms of average maximum WL and iron has approximately the
same value as the pooled average. For commodities with only one or two
observations the highest was antimony followed by copper, tungsten, and
28
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silver. The single available maximum WL observation for antimony is 0.91; the
average for two copper values is 0.70; the average for two tungsten values is
0.61 and for silver is 0.24. When analyzed in terms of WL and rejecting
single values, the commodities with.possibly the greatest air concentration of
radon-222 progeny are: 1) molybdenum, 2) copper, 3} tungsten, and 4) iron.
The radium-226 data base from water samples is extremely incomplete. For
all commodities pooled, the average radium content is 17.3 pCi/1. If the
extremely high value in a gold mine is excluded (81.7 pCi/1), the average
radium content is 9.2 pCi/1. Data values appear to be extremely high or low
(see Appendix A). If observed radium-226 activity in water from various parts
of the metallic mineral extraction industry are indicative, radium-226 content
of water sampled is elevated and in general would exceed the 5 pCi/1 standard.
Such a direct comparison is probably not strictly valid particularly
considering that the waters tested are not intended for potable use.
Nevertheless there is some possibility that a radiological health hazard may
exist in process water associated with metallic mineral extraction operations.
Radium-226 data ranked in decreasing concentration for these commodities with
observations greater than 9.2 pCi/1 are: 1) gold, 2) iron, 3) molybdenum, and
4) aluminum.
Among the nonmetallic commodities, fluorspar appears to have significantly
greater concentrations (1.2 WL) in mine atmospheres (Table 5), although these
are associated with low ventilation rates. The Federal Radiation Council
(1967) reported that radon in a fluorspar mine in Newfoundland in areas of
restricted ventilation exceeded 1000 pCi/1. Also, tailings from a fluorspar
operation near Golden, Colorado have gamma radiation levels on the order of
29
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1 mR/h (USEPA, 1976). The pooled average maximum WL for nonmetallics was 0.56
which is very close to 0.54 observed for the metal lies. The highest number
reported was 1.6 WL for a phosphate mine, but since phosphates are excluded
from this discussion, this value will not be used. Outside of these two
observations maximum working levels are much lower, possibly indicating that
fewer nonmetallic mine and milling operations bear much additional study.
Robbins (written communications, 1977) noted that MSHA also reported signif-
icant amounts of radon-222 in fluorspar related mines with about 500 pCi/1
reported. Similarly, about 100 pCi/1 radon-222 was noted in underground
granite, marble, and limestone operations.
30
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SUMMARY
CONCLUSIONS
1. The overall geochemical properties of uranium and thorium suggest that
cerium, zirconium, and the rare earth elements should be associated.
2. Uranium and thorium content of igneous rocks generally increases with
increasing silica and with increasing potassium. Some mafic and accessory
minerals are much more enriched than the felsic minerals. Thorium content of
igneous rocks closely follows the potassium content.
3. Certain areas such as the Front Range in Colorado and portions of New
England are broad regions of overall enrichment in uranium and thorium.
4. Pegmatites may be enriched in uranium, particularly if the potassium
content is elevated.
5. Carbonatites can be enriched in uranium and thorium, particularly if
rare-earth content is high.
6. Some rare-earth elements have radioisotopes which may contribute to
overall radioactivity of an REE ore body.
31
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7. Hydrothermal mineral deposits exhibit a broad spectrum of geochemical
and mineralogical association with thorium and uranium. The three principal
metals observed in vein type uranium deposits are iron, copper, and lead.
Uranium minerals have been found in many different types of deposits including
ores for gold, silver, and iron.
8. The distribution of trace amounts of uranium is homogeneous in pyrite,
sphalerite, and galena at concentrations less than 8 ppm uranium. Trace
amounts of uranium greater than this are irregularly distributed and
presumably not strongly related to the deposition of the host minerals.
9. Fluorspar deposits appear to be more radioactive than most other non-
metallic ores. Both thorium and uranium minerals have been observed with
fluorite.
Fluorspar deposits have been noted as having significant radioactivity
in associated underground mine atmosphere and mine tailings. Radioactivity of
fluorspar deposits has been suggested as a useful exploration tool.
10. Uranium is generally soluble and mobile in the sedimentary cycle.
Uranium may be stabilized by organic matter. Thorium minerals are resistant
to surface weathering and tend to be concentrated in placers or in residual
soil (such as bauxite).
11. Byproduct recovery of uranium from phosphate, copper, and gold ore
processing is underway and is proposed for beryllium ore.
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12. With the exception of uranium and phosphate ore bodies and to a lesser
extent in the case of placer deposits of resistate minerals, no persistent
pattern of radioactivity is associated with ore bodies. Radioactivity may
vary substantially between ore bodies with similar mineralogy and genesis.
Mines of gold, copper, and iron have been observed with elevated
radioactivity.
13. Observations on radioactivity of mine atmospheres are of questionable
validity. Preliminary information suggests that higher working levels are
associated with molybdenum, copper, tungsten, and iron.
14. Radium-226 observed in various types of mine related water tends to be
elevated. The highest concentrations observed, in descending order, are gold,
iron, molybdenum, and aluminum.
RECOMMENDATIONS
1. Radiological surveys of various mining industries need to be made for
both the uranium and thorium decay series. Rare-earth element radioisotopes
and potassium-40 may be important in certain situations,
2. Atmospheric radioactivity levels in underground mines may be poorly re-
lated to ore geochemistry. Radon levels have been found to be substantial in
limestone caves despite the fact that limestone has low concentrations of both
uranium and thorium (see Table 3). Detailed information is required on
ventilation before valid conclusions can be attempted.
33
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3. Mineral extraction appears to enhance radium-226 concentrations in mine
related water. Further investigation is appropriate in this area.
34
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Jennings, J. K., and J. S. Leventhal, 1977, A new structural model for humic
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Short papers of the U.S. Geological Survey Uranium-Thorium Symposium, 19777
U.S. Geol. Survey Circ. 753, p. 10-11.
Jensen, M. L., 1958, Sulfur isotopes and the origin of sandstone-type uranium
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Kaufmann, R. F., and J. D. Bliss, 1977, Effects of phosphate mineralization
and the phosphate industry on radium-226 in ground water of central Florida,
U.S. Environmental Protection Agency, report no. EPA/520-6-77-010, 115 pp.
King, R. U., B. F. Leonard, F. B. Moore, and C. T. Pierson, 1953, Uranium in
the metal-mining districts of Colorado: U.S. Geol. Survey Circ. 215, 10 pp.
Krauskopf, K. B., 1967, Introduction to geochemistry; McGraw-Hill, New York,
721 pp.
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Can. Geol. Survey Econ. Geol. Ser. No. 16, 173 pp.
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the Front Range mineral belt, Colorado (abs.); Econ. Geology, v. 47, p. 773.
Lowder, W. M., and L. R. Solon, 1956, Background radiation a literature
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p. 375-380.
Mason, B., 1966, Principles of geochemistry: John Wiley & Sons, New York,
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McKelvey, V. E., 1955, Search for uranium in the United States: U.S. Geol.
Survey Bull. 1030-A, 64 pp.
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38
-------
Moxham, R. M., R. S. Foote, and C. M. Bunker, 1965, Gamma-ray spectrometer
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39
-------
Polanski, A., 1965, Geochemistry of isotopes: TT61-31327 (Engl. Trans!.),
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Prof, paper 1050, p. 28.
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deposits, Miami District, Arizona; Unpub. Ph.D. Thesis, Harvard University.
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Sources and effects of ionizing radiation; Report to the General Assembly,
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40
-------
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Survey Prof. Paper 933, p. 14-15.
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p. 593-596.
Vine, J. D., 1956, Uranium bearing coal in the United States, in Contributions
to the geology of uranium and thorium by the United States Geological Survey
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Survey Prof. Paper 300, p. 405-411.
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fluorite deposits: U.S. Geol. Survey Circ. 220, p. 13-18.
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Geological Congress Report of the Twenty-First Session, Part XVI: Theodor
Sorgenfrei, ed., p. 248-260.
41
-------
APPENDIX A. RADIOLOGICAL DATA FOR SELECTED METALLIC COMMODITIES
Commodity
Al uml num
Antimony
Copper
Gold
State - Mine
Arkansas
Bauxite
Montana
Babbitt
Arizona
Mammoth Mt.
Bagdad
Copper Queen
(& Silver) Red Rover
Michigan
White Pine
Montana
Butte
Tennessee
Boyd
Colorado
Brooklyn
Nevada
(& Silver) Gooseberry
Oregon
Buckeye
Bald Mountain
South Dakota
Homestake
Water Type
Mine
Wastewater
Basin c(?)
300 Level, Mine
Pit Mine
Discharge #1
Discharge #2
Discharge #3
Mine
Mine
Mine
Input to emergency
pond
Mine
Radium -226 Atmospheric Radioactivity*
pCi/1 WL Observed
32.2 +
2.15 +
4.6 +_
2.6 +
1.6 +
27.3 +
4.18 +
13.6 +
4.79 +
1.52 +
2.95 +
1.72 +_
81.7 +
2.3
.22
.62
.26
.16
2.7
.46
1.4
.48
.15
.53
.17
8.2
.47 (.91)
Yes**
- (1.2)
.089(.207)
.15 (1.15)
.17 (.2)
.13 (.13)
.17 (.32)
Footnotes - See end of Appendix
-------
APPENDIX A. RADIOLOGICAL DATA FOR SELECTED METALLIC COMMODITIES (Continued)
Commodity
Iron
(Magnetite)
Lead/Zinc
(Lead/Silver)
(Zinc Only)
(Zinc Only)
(Zinc Only
(Lead Only)
(Lead Only)
(Lead Only)
(Lead & Silver)
State - Mine
Michigan
Mather B
Sherwood
Missouri
Pilot Knob
Pea Ridge
Pennsylvania
Grace
Colorado
Leadville Unit
Idaho
Kellogg
Muldoon Barium
Silver Empire
Horseshoe
Tamarack
Star
Bunker Hill
Missouri
Bixby
Indian Creek
Viburnum #27
Viburnum #28
New York
Balmat
Oklahoma
Eby
Pennsylvania
Central Valley
Utah
Deertrail
Washington
Pend Oreille
Radium-226
Water Type pCi/1
Mine 16.6 + .7
Mine 3.01 _+ .30
Mine/Mill (treated) <1
Pond Effluent <1
Mine Drainage 27.8 _+ 2.8
Mine <1
Atmospheric Radioactivity*
WL Observed
.21 (.49)
.51 (.9)
- (.26)
- (.642)
.14 (.14)
.21 (.42)
- (.23)
.37 (.37)
(.18)
•2 (.7)
.08 .2)
.07 (.2)
^ (.17)
- (-11
- (.15)
Yes**
- (.25)
.70 (1.4)
Footnotes - See end of Appendix
-------
APPENDIX A. RADIOLOGICAL DATA FOR SELECTED METALIC COMMODITIES (Continued)
Commodity
Molybdenum
Nickel
Silver
Tungsten
Vanadium
State - Mine Water Type
Colorado
Climax Mine
Henderson
Idaho
TFompson Creek
Oregon
Nickel Mountain Slag
Idaho
Sunshine Mine
Silver Empire
Crescent
California
Pine Creek
Nevada
Emerson
Arkansas
Garland Operation Mine
Radium -226
pCi/1
15.8 ± 1.6
8.23 + 83
4.47 + .45
2.44+ .5
Atmospheric Radioactivity
WL Observed
.24 (.38)
.21 (1.56)
- (.54)
.37 (.37)
.04 (.10)
.31 (.72)
.1 (.5)
"*Underground operations, Average WL followed by maximum WL in brackets.
Yes - R. Rock, MSHA, 1977, indicated that significant atmospheric radiation was observed but no
quantitative measurements are available.
**
-------
APPENDIX B. RADIOLOGICAL DATA FOR SELECTED NONMETALLIC COMMODITIES
Commodity
Clay
Fluorspar
Gypsum
Limestone
Phosphate
Silica Sand
Talc
State - Mine Water Type
Pennsylvania
Kitanning
Continental Clay
Ohio
Dando
Irondale
Strong Creek Brick
West Virginia
Globe Clay
Arizona
Western Fluorspar
Colorado
Burlington
Nevada
Crowell Fluorspar
Texas
Paisano Underground
Virginia
No. 6 Mine
Illinois
Alton
Montana
Brock -Warm Springs
Wisconsin
Bay City Sand
Vermont
Windham
Radium-226 Atmospheric Radioactivity*
pCi/1 WL Observed
**
Yes
.4 (.4)
.37 (.46)
.10 (.13)
.18 (.24)
.3 (.3)
.9 (2.2)
Yes
.9 (1.0)
.3 (.41)
.28 (.30)
.05 (.16)
.75 (1.6)
.13 (.19)
•18(-)
* Underground Operations, Average WL followed by maximum WL in brackets
** Yes - R. Rock, MSHA, 1977, indicated that significant atmospheric radiation was observed
-------
APPENDIX C. GLOSSARY OF GEOLOGICAL TERMS USED
ALLANITE - A mineral of variable composition of the epidote group with general
formula (Ca, Ce, La)£(Al , Fe, MgJ3(Si04)3 (OH); may contain Th as much
as 3.2 percent.
APATITE -A mineral group with the general formula 035^04)3
(OH, F,C1). Fluorapatite [Cas(P404)3F] is by far most common and
apatite is used synonymously with fluorapatite.
BASE METAL - Metal of less value than gold or silver; generally considered to
be one of the following: copper, lead, zinc, tin, or mercury.
BASTNAESITE - A complex fluorcarbonate of the rare-earth elements principally
cerium and lanthanum and usually less than one percent uranium and thorium;
occur in metamorphic contact zones.
BATHOLITH - A body of intrusive rock at least 40 square miles in surface ex-
posure.
BAUXITE - A rock composed of aluminum hydroxides and impurities in the form of
free silica, clay, silt and iron hydroxides; the principle ore of aluminum.
BERYL - A mineral with the formula Be3Al2(Si60is) but may also contain
Na, Li, Cs and occasionally Rb.
BIOTITIC -Containing biotite, an iron rich tri-octahedral mica.
CARBONATITE - An intrusive igneous rock of high carbonate content and usually
enriched in a wide range of rare elements.
CENOZOIC ERA - The time interval covering the last 60 million years.
CHLORITIC - Containing chlorite, a mica-like mineral of the formula (Mg, Al,
Fe)12 [(S1,A1)80203 (OH)16.
CLAY -Crystalline fragments of minerals that are essentially hydrous aluminum
silicates or hydrous magnesium silicate.
COLUMBITE - A mineral, the Nb - rich end member of the columbite - tantalite
series (Fe,Mn) (Nb,Ta)206.
CONGLOMERATE - A rock made up of pebbles and other rock fragments (usually
rounded) cemented together.
DETRITAL - Consisting of mineral or rock fragments.
46
-------
EPIGENETIC - Refers to a process in which minerals undergo changes as result
of external processes usually at or near the earth's surface.
EPIDOTE - A mineral of the formula Ca2(Al, Fe+3)3(Si04)3(OH).
EUXENITE - A complex oxide mineral containing thorium, rare-earths, niobium,
tantalum, calcium and titanium; occurs as an accessory mineral in granitic
rocks.
FELDSPAR -A group of minerals commonly in most rocks with the general formula
XA1(A1 ,Si)30s where X = K, Na, Ca as the major ions, and Ba, Rb, Sr as
trace ions usually less than 1500 ppm.
FLUORAPATITE - A mineral of the apatite group with the formula
Ca5(P04)3F.
FLUORITE - See Fluorspar below.
FLUORSPAR - A mineral, CaF2, the principal ore of fluorine.
FLUVIAL - Of, or pertaining to, rivers; produced by river action.
FRACTIONATION - The process by which a mixture is broken down into components.
GALENA - A mineral with formula PbS.
GARNET - A mineral group, with a general formula X3Y2(Si04)3 where
X = Ca, Mg, Fe+2, and Mn+2; Y = Al , Fe+2. ,Mn+2, and Cr.
GRANITE - A silica rich igneous rock with minerals discernible to the naked
eye consisting of alkali feldspar and quarts with minor muscovite, biotite,
and hornblende.
HURONIAN - A subdivision of Precambrian rocks identified in the Canadian
Shield which range from about 800 to 1200 million years in age.
IGNEOUS - Formed by solidification from a molten or partly molten state.
ILMENITE - A mineral with the formula FeTi03; accessory mineral in many ig-
neous and metamorphic rocks.
LIGNITE - Brownish -black coal composed of a plant residue more altered than
peat but less than bituminous coal; less than 8300 BTU.
LIMESTONE - Sedimentary rock consisting mainly of calcium carbonate (CaC03).
MAGNETITE - A magnetitic iron mineral, FeFe*, occurring as an ac-
cessory mineral in igneous rocks and as an iron ore.
MAGMATIC DIFFERENTIATION - Operation by which various types of igneous rocks
are separated from a single molten mass.
47
-------
MARBLE - A rock, metamorphosed limestone or dolostone with more or less
course -grained crystalline structure.
MARCASITE - A mineral of the formula Fe$2; pyrite is a different crystal
form of the same chemical composite.
MICA -A mineral group of phyllosil icates with sheet -like structures.
MINERAL -A naturally occurring chemical element or compound having a definite
range in chemical composition and characteristic crystal structure.
MONAZITE - A mineral (Ce,La)P04 commonly containing thorium as well as rare
earth elements.
MUSCOVITE - A mineral of the mica group (which are characterized by a sheet-
like structure) of the general formula KAl£
OPALITIC -A material consisting of opal, with amorphorus hydrated silica
PHLOGOPITE - A mica mineral with the formula K2(Mg, Fe+2)6
(OH,F)4.
PITCHBLENDE - Another term for uraninite when massive.
PRECAMBRIAN -All geologic time previous to about 600 million years ago.
PYRITE - A mineral of the formula Fe$2 the most abundant sulfide.
QUARTZ - A mineral, $104.
QUARTZITE - A rock of quartz grains bonded by metamorphism.
QUARTZ MONZONITE - An igneous rock (with minerals identifiable with the naked
eye) which contains plagioclase (Na/Ca feldspar), orthoclase (K feldspar), and
quartz with biotite and/or hornblende and accessory apatite, zircon and opaque
oxides.
RESISTATE MINERALS - Those undecomposed residues of weathering.
ROCK - Any natural aggregate of mineral matter (or single mineral) con-
stituting an essential part of the earth's crust.
RUTILE - A mineral, Ti02.
SPECIFIC GRAVITY - Ratio of the mass of a body to the mass of an equal volume
of water at a specified temperature.
SPHENE - A mineral with the formula
SPODUMENE - A mineral with the formula LiAlSi206.
THORITE - A mineral with the formula ThSi04.
48
-------
TOURMALINE - A mineral, a complex borosllicate containing varying amounts of
Na, Mg, Fe, Mn, Li, and Al.
URANINITE - A mineral, primarily U02 but also may contain Th, rare-earths,
Ra, and Pb.
VEIN DEPOSIT - A mineralized zone long in two dimensions and thin in the
third.
WEATHERING - Chemical and physical processes operating at the earth's surface
on rocks resulting in change in character, decay, and finally crumbling into
soi 1.
XENOTIME - A mineral YP04 also containing rare-earths, Th and U.
ZIRCON - A mineral, ZrSi04, a common accessory mineral, particularly in
silica enriched plutonic rocks.
Principal Sources:
American Geological Institute, 1962, Dictionary of geological terms; Dolphin
Books, Garden City, NJ, 545 pp.
American Geological Institute; 1976, Dictionary of geological terms; Anchor
Press, Garden City, NJ, 472 pp.
Deer, W. A., Howie, R.A., and J. Zussman, 1966, An introduction to the rock
forming minerals; John Wiley and Sons, New York, 528 pp.
Leet, L. D., and S. Judson, 1965, Physical Geology; Prentice-Hall, Englewood
Cliffs, NJ, 406 pp.
Moore, R. C., 1958, Introduction to Historical Geology, McGraw-Hill, New York,
656 pp.
49
-------
TABLE 1. URANIUM AND THORIUM CONTENT OF MINERALS
FOUND IN IGNEOUS ROCKS *
Major Mineral
Quartz
Feldspar
Biotite
Muscovite
Hornblende
Pyroxene
Uranium ***
Mean (ppm)
1.7
2.7
8.1
7.9 (?)
3.6
0.05
Uranium Thorium
Normal Range (ppm)**
0.1-10
0.1-10
1.0-60
2-8
0.2-60
0.1-50
0.5-10
0.5-10
0.5-50
-
5-50
.
0.02
01ivine
(mean)
* Summarization of tables given in Rogers and Adams (1969a; 1969b)
** Normal range excluding extreme values
*** Recent work suggests that the quartz and feldspar values are too high,
biotite is low by order of magnitude and pyroxene high by order of magnitude
(Stuckless, 1978 written communication)
TABLE 2. GENERALIZED DISTRIBUTIONS OF URANIUM IN VARIOUS
GROUPS OF IGNEOUS ROCKS
Ultramaflc rocks
(dunltes, serpenUnites,
ecfogfles, etc.)
Mafic rocks (basalts, gabbros etc.)
Intermediate rocks (andesites, dacites,
rhyodacites, diorltes, quartz diorites,
granodiorites, etc.)
Silicic rocks (quartz latites, rhyolites,
quartz monzonites, granites)
0.001 0.01 0.1 1.0
Uranium (ppm)
(Taken from Rogers and Adams, 1969b)
50
10
-------
TABLE 3. URANIUM AND THORIUM CONTENT OF SELECTED
SEDIMENTARY ROCKS*
Rocks
Sandstones
Orthoauartzite
(North American Avg.)
Graywacke (Est. Avg.)
Arkose
Thorium (ppm.) Uranium (ppm)
1.7
2.8
5
0.45
2.1
1.5
Shale
Common Shale, Gray, Green, etc.
(North American Avg.)
Black Shale
Bauxites
Bentonites
Limestones (North American Avg.)
Dolomites (Range)
Phosphate Rock (Range)
Evaporites**
13.1
Low
48.9
24.0
1.1
-
1-5
3.2
8
11.4
5
2.2
0.03-2.0
50 -300
generally less
than 0.1
* Summarization of tables given in Rogers and Adams (1969a, 1969b)
** Some evaporites can be important ore deposits particularly those found in
Africa and Australia (Stuckless, 1978, written communication).
51
-------
Ln
tN)
TABLE 4. SUMMARY OF RADIOLOGICAL INFORMATION ON METALLIC COMMODITIES
GIVEN IN APPENDIX A
Commodity
Aluminum
Antimony
Copper(3)
Gold(4)
Iron(5)
Lead/Zinc(6)
Molybdenum
Nickel
Silver
Tungsten
Vanadium
Average Maximum(l) Number of
WL Observed
Observations
Radium-226(2)
pCi/1
(2.44)(8)
Number of
Observations
-
.91
.70
.20
.48
.37
.83
-
.24
.61
-
1
2
4
5
12
3
-
2
2
13.0
-
6.7
81.7
16.7
(6.46)(7)
15.8
8.34
4.47
«.
3
-
9
1
1
5
1
1
1
„
(1) Underground operation, Goodwin, MSHA, written communication, 1978; (2) Calspan Corporation,
1975, (3) Includes a copper and silver mine; (4) Includes a gold and silver mine; (5)
Includes a magnetite mine; (6) Includes 3 zinc only mines, 3 lead only mines and a lead/
silver mine; (7) Less than 1 pCi/1 replaced with .5 pCi/1 in calculation; (8) Composite
of two samples.
-------
TABLE 5. SUMMARY OF RADIOLOGICAL INFORMATION ON NONMETALLIC
COMMODITIES GIVEN IN APPENDIX B
Average Maximum* Number of
Commodity WL Observed Observations
Clay 0.3 5
Fluorspar 1.2 3
Gypsum 0.30 1
Limestone 0.16 1
Phosphate 1.6 1
Silica Sand 0.19 1
Talc (0.18)** 1
* Underground operation, Goodwin, MSHA, written communication, 1978
** Average WL, maximum value not available
53
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing!
1. REPORT NO.
ORP/LV-79-1
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Radioactivity in Selected Mineral Extraction
Industries - A Literature Review
S. REPORT DATE
Nnvpmher 1
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
James D. Bliss
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Office of Radiation Programs - Las Vegas Facility
U.S. Environmental Protection Agency
P.O. Box 15027
Las Vegas, NV 89114
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Final
Same as above
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The mining, milling, and processing of mineral resources may cause varying
degrees of technologically enhanced natural radioactivity (TENR) which is de-
pendent on the inherent uranium and thorium content of the target resource and
the details of the total extraction process.
[The objective of this review is to identify from the available domestic
literature possible metallic and nonmetallic mineral extraction industries
(exclusive of uranium, phosphate, and fossil fuels) which may require sub-
sequent assessment.! Certain industries such as phosphate and coal are already
identified as potential sources of radioactivity; hence, they are excluded from
this overview.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Geology and mineralogy
Radioactive materials
Mineral deposits
0807
1808
0807
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (ThisReport)
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS COITION is OBSOLETE
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United Stales
Environmental Protection
Agency
Office of Radiation Programs
Las Vegas Facility
PO Box 15027
Las Vegas NV 891 14
Official Business
Penalty for Private Use
S300
Postage
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