Iron

The WSGS completed its investigation into the iron resources of Wyoming in 2015 with the publication of its Report of Investigations No. 67. The goal of the study was to consolidate and correct information on iron from a wide variety of earlier investigations, the latest of which was published by the U.S. Bureau of Mines in 1976. WSGS RI-67 not only fulfills that goal, but also provides better perspective on iron resources throughout Wyoming along with new site information and multi-element analyses that were previously absent or incomplete.

Iron has been a significant resource in the history of Wyoming, providing raw material, jobs, and economic development. The earliest iron mining and use was by Paleo-Indians in the Sunrise area, in southeast Wyoming for iron oxide pigment between 8,000 and 13,000 years ago. In the late 1800s, Wyoming produced concretionary hematite from the Rawlins area for use as paint pigment and smelting flux.

Titaniferous magnetite, identified prior to 1850, has been mined sporadically from magmatic segregation deposits in the Iron Mountain area for use as a weighting additive in cement. Archean banded iron formation (BIF) mined in both the Hartville Uplift, between 1899 and 1980, and near South Pass, from 1962 to 1983, accounted for more than 132 million tons of iron ore, shipped out of state for iron and steel manufacture. Over time, numerous smaller deposits across the state have also been investigated as potential sources of iron.

Wyoming currently has no active iron mines but does have in-place iron ore resources that may have future economic viability. For example, iron deposits at South Pass and in the Hartville Uplift have not been mined out and still contain large amounts of iron ore. Numerous small iron occurrences are known across Wyoming, and recent exploration has identified at least one potentially large and previously unknown deposit in the Rattlesnake Hills-Granite Mountain area in central Wyoming.

All known iron occurrences from various resources have been compiled and summarized in sections of WSGS RI-67. Analytical data is presented within the text of the report, and complete analyses are included in the appendix.

Elemental iron is the fourth most abundant element in the earth’s crust at about 5 percent and is most commonly found combined with oxygen in the form of iron oxide minerals, particularly magnetite and hematite. The demand for iron fluctuates as second and third world countries urbanize and continue developing. Iron will likely always remain a necessity for everyday life on a global scale. It is integral to products that range from paperclips and metal alloys to cosmetics, fertilizer, and animal feed. A wide variety of uses for iron is shown in the following table:

Uses for Iron

Iron (III) Acetate	dyes, mordants
Iron Arsenate	pesticides
Iron (III) Chloride	sewage treatment, dyes, animal feed additive, electronic etching, catalyst
Iron Hydroxide	water purification systems
Iron (III) Phosphate	molluscicides, corrosion resistance/rustproofing, adhesive, battery electrodes
Iron (II & III) Sulfate	dyes/stains, black ink, treatment of anemia, sewage and water treatment, reducing agent, fertilizer, herbicide, food fortification, preservation of wood paneling
Cast Iron	frying pans, griddles, skillets, Dutch ovens, waffle irons, pipes, auto parts, building construction, slurry pumps, ball mills, pulverizers
Metallic Iron	permanent and electro magnets
Stainless Steel	cutlery, surgical instruments, cookware, appliances, architecture, sculptures, railcars, automotive bodies, fibers, guns, watches
Steel	pipes, construction, heavy equipment, furniture, steel wool, tools, armor, bolts, nails, screws, appliances, wire, railroad tracks, reinforcing mesh/bars, automobiles, trains, ships, magnetic cores
Wrought Iron	fences, furniture, home decor
Miscellaneous	coal washing, drilling mud/high density slurries, abrasives/polishing compounds, thermite/welding, magnetic tape and recordings, filtration, photocatalyst, calamine lotion ingredient

Gold in Wyoming

Gold, the intrinsically valuable "royal metal," derives its value from the combination of its rarity and beauty along with its softness (2.5 to 3 on the mohs hardness scale), malleability, ductility, ease of alloying with other metals such as copper and silver, and its high resistance to corrosion and tarnish. Various estimates place the average gold content of the earth’s crust around 3.1 parts per billion (ppb), or roughly 0.0001 ounce/ton. Although disseminated gold is widely distributed, concentrations greater than 0.5 ppm, or 0.5 g/tonne, are near minimum for economic recovery in a modern low-grade, large-tonnage gold mine. Higher grades are always desirable and are usually necessary to initiate mining prior to recovery of the lowest grade material.

Gold has a specific gravity of 19.3 – much heavier than the specific gravity of quartz (2.65), a common host rock for gold. Other host rocks may be heavier than quartz, but even the heaviest, such as banded iron formation, have specific gravities less than half that of gold. The great difference in weight between gold and its host rocks allows it to concentrate in placer deposits from which it can easily be recovered. Since earliest times, gold has been used for both objects of art and for coinage.

Gold and other metals have been mined from primary deposits in Precambrian rocks exposed in the cores of Wyoming’s mountain uplifts and in some Tertiary volcanic and intrusive rocks. Gold has also been mined from placer deposits concentrated by weathering and erosion of those primary occurrences.

History

Around 1842, travelers along the old emigrant trail (part of the Oregon Trail) first reported placer gold near the Sweetwater River in the area now known as the Lewiston district, near the southern tip of the Wind River Range (see Principal Metal District Map). Indian hostilities prevented serious prospecting until the 1860s. Wyoming’s first gold rush sprang from the 1867 discovery of bedrock-hosted gold west of the Lewiston district in what became the famous Carissa lode.

In 1869, the settlements of South Pass, Atlantic City, and Miners Delight boasted a combined population of more than 2,500. Gold production from the Carissa totaled between 50,000 and 180,000 ounces before 1911. Total production from Wyoming is unknown because no records were kept, and few estimates were made before about 1900.

Mining districts were organized in several locations across Wyoming during the late 1860s and 1870s. The South Pass-Atlantic City district was first and foremost. Other districts discovered during that era of relatively high gold prices included Lewiston (about 12 miles southeast of the South Pass-Atlantic City district); Centennial Ridge, Douglas Creek, Gold Hill, Keystone, and New Rambler (all in the Medicine Bow Mountains); Seminoe Mountains; Copper Mountain in the Owl Creek Mountains; and Mineral Hill in the Black Hills. Recent gold exploration activity in Wyoming has emphasized both historic mining districts as well as newer discoveries.

Wyoming gold districts are included within the principal metal districts and mineralized areas (see Principal Metal District Map) but may represent more detailed subdivisions. These gold districts are discussed under headings of some of Wyoming’s mountain ranges, including Wind River Range, Medicine Bow Mountains and Sierra Madre, Absaroka Mountains, Laramie Mountains, Rattlesnake Hills, and the Bear Lodge Mountains (see separate tabs on this page).

The dramatic rise of gold prices beginning in 2005 led to renewed interest in Wyoming gold. Individual prospectors, recreationists, and a few major companies have recently explored historic gold districts and potential new deposits.

Precious Metal Purity

Fineness and Karats	Percent Gold
999, 24	99.9%
990, 23.8	99%
916.67, 22	91.6%
900, 21.6	90%
875, 21	87.5%
833, 20	83.3%
750, 18	75%
583.30, 14	58.3%
500, 12	50%
416.67, 10	41.7%

Fineness refers to the purity of precious metal contained in an alloy as parts per thousand. A purity of 99.9% precious metal is 999 fine, which may be written in decimal form as .999 fine. A precious metal containing 10 percent other metals is said to be 900 fine or to have a fineness of 900.

Purity of a gold (or platinum) alloy may also be stated in karats. One karat is 1/24 part by weight of the total mass; pure gold (999 fine to 1000 fine) is 24-karat gold. 18-karat gold is an alloy of 75% gold or 750 fine. The spelling "carats" is used outside of the United States and Canada and should not be confused with the carat weight used for gemstones. A karat designation of purity is accompanied by the abbreviation K (or ct).

Old mines are often a good place to begin prospecting. Information on most of Wyoming’s gold and precious metals deposits can be found in the following recommended publications by the Wyoming State Geological Survey:

Hausel, W.D., 1989, The geology of Wyoming’s precious metal lode and placer deposits: Geological Survey of Wyoming [Wyoming State Geological Survey] WSGS Bulletin 68, 248 p., 6 pls.

Hausel, W.D., 2002, Searching for gold in Wyoming: Wyoming State Geological Survey Information Pamphlet 9, 12 p.

Additional references relating to gold and other metals in Wyoming are found on the References Page.

Southern Wind River Range

The historic South Pass-Atlantic City and Lewiston districts are characterized by abundant small lode and placer deposits with additional potential for large-tonnage, low-grade mineralization and small undiscovered high-grade deposits. This area is a greenstone belt that forms a synclinorium of metamorphosed sedimentary, volcanic, and plutonic rocks intruded by granitic plutons. Gold mineralization occurs mainly in foliation-parallel shear zones and is associated with quartz, sulfides, carbonates, and related wallrock alterations. An estimate by Hausel (1989) suggests that as much as 334,000 ounces of gold were mined from the South Pass-Atlantic City district.

Placer and paleoplacer gold deposits are widespread in the vicinity of the greenstone belt. The Oregon Buttes-Dickie Springs paleoplacers are a few miles south of the South Pass-Atlantic City district. Love, Antweiller, and Mosier (1978) described these paleoplacers as hosting as much as 28.5 million ounces of placer gold.

Medicine Bow Mountains and Sierra Madre

The Medicine Bow Mountains and Sierra Madre are Precambrian-cored Laramide uplifts that straddle the margin of the Wyoming craton. The Wyoming craton was established more than approximately 2.7 billion years ago (2.7 Ga, or Giga-annum), but was later affected by a regional metamorphic event 1.9–1.7 Ga. The south boundary of the Wyoming Craton in the Medicine Bow Mountains and Sierra Madre terminates against the Mullen Creek-Nash Fork shear zone. This shear zone, which forms part of the Cheyenne belt suture, represents a continental-arc collision zone separating the Wyoming Province to the north from cratonized (1.7 Ga) Proterozoic basement of the Colorado Province to the south.

Within the Colorado Province south of the Cheyenne belt, metavolcanic and metasedimentary rocks provide excellent hosts for magmatic massive sulfide mineralization (copper, zinc, lead, silver, gold) and some shear zone copper, gold, and associated gold placers. Layered mafic-ultramafic intrusives, ultramafic massifs, and fragments with platinum, palladium, gold, silver, copper, titanium, chromium, and vanadium anomalies occur within the Proterozoic terrain – most notable are the Mullen Creek, Lake Owen, and Puzzler Hill complexes. The New Rambler mine is located along the northeastern edge of the Mullen Creek mafic-ultramafic complex in the Medicine Bow Mountains and is Wyoming’s only mine known to have historically produced platinum and palladium. The mineralization, occurring in hydrothermally altered mafic shear-zone cataclastics, may have been remobilized from the layered complex. Because of their high potential for platinum-palladium mineralization, Mullen Creek, Lake Owen to the east, and Puzzler Hill in the Sierra Madre continue to be platinum exploration targets.

North of the Cheyenne belt in the Medicine Bows and Sierra Madre, the Wyoming Province includes amphibolite-grade schists and gneisses overlain by younger Archean and Proterozoic metasedimentary and metaigneous rocks. Metaconglomerates found in several of the Precambrian units are considered potential sources for uranium, thorium, and rare earth elements. Similarities between these rocks and the gold-rich quartz-pebble metaconglomerates of the Witwatersrand, South Africa, suggest that they also have potential to host significant copper, gold, and silver mineralization.

During the late 1800s and early 1900s, intense prospecting left numerous remnants of mines and prospects concentrated in the broad region underlain by sheared rocks of the Cheyenne belt, although scattered mineralization occurs throughout both mountain ranges. There is no evidence that any of the significant historical mines, with the exception of the Centennial mine, were ever mined out. Mine operations usually ceased due to factors such as declining metal prices, lack of technological developments, ore complexity below the zone of oxidation, outbreak of war, and other political or human-related factors. The Centennial mine ceased operations because the mineralized lode was offset by faulting. The extension of the ore deposit was never found.

Centennial Ridge District

Placer gold, discovered in gravels along the Middle Fork of the Little Laramie River, led to the organization of the Centennial Ridge mining district in the east-central Medicine Bow Mountains in 1876. Placer activity was followed by several lode discoveries including the Centennial mine. A new wave of prospecting and development followed the 1901 discovery of platinum associated with copper ores at the New Rambler mine 5 miles to the southwest. Structural fabric within the district is generally northeast-trending and parallel to the Cheyenne belt. Lode mineralization includes foliation/schistosity parallel gold-bearing quartz veins in biotite and hornblende gneisses and schists, and gold-platinum fracture-filling and replacement veins in shear zones and faults cutting the gneisses and schists. Sulfides and arsenides accompany gold-platinum in the fracture fillings. Sulfide-rich zones, dominated by pyrite and occurring in mafic host rocks, usually accompany the richest ores in the district. Actual production from the Centennial Ridge district is unknown. However, the Centennial mine produced an estimated 4,500 ounces of gold.

Douglas Creek District

The Douglas Creek district in the central Medicine Bow Mountains includes all placer deposits along Douglas Creek and its tributaries, from Rob Roy Reservoir southward for 6 miles to below Lake Creek. Gold was discovered in Moore’s Gulch, a tributary of Douglas Creek, by Iram Moore in 1868. Lode gold discoveries in both the New Rambler and Keystone districts resulted from placer gold being traced upstream to its primary sources. Heavy placer activity along the creek included elaborate hydraulic ditches in use by 1876. Resurgent placer activities during the 1930s, 1940s, and 1950s used gasoline-powered draglines and floating washing plants. Gold recovered from gravels up to 20 feet thick varied from 890 to 960 fine, with some silver and traces of platinum. Currey (1965) estimated total gold production from the Douglas Creek placers at about 4,000 ounces. The Douglas Creek district remains a popular area for amateur placer mining.

New Rambler District

The New Rambler district, just west of Douglas Creek, is near the south edge of the Cheyenne belt along the Rambler shear zone, an east-trending branch of the Mullen Creek-Nash Fork shear zone. The Rambler shear zone, numerous local northeast-trending shears, and a few northwest-trending faults cut foliated granodiorite, the younger Rambler Granite, and the distorted northeast extremities of the Mullen Creek mafic-ultramafic complex.

Primary copper sulfides and gold occur in quartz veins, as fracture fillings, and in zones of brecciation. Significant secondary mineralization, found only in the New Rambler mine, often assayed more than 35 percent copper. The New Rambler mine first opened as a gold mine in 1870. Copper was discovered in 1900 at a depth of 65 feet, and platinum within the covellite ore was discovered in 1901. Estimated production from the New Rambler mine totaled 171.3 ounces of gold, 7,346 ounces of silver, 1,753,924 pounds of copper, 910 ounces of platinum, and 16,870 ounces of palladium. The New Rambler area is considered an attractive target for platinum group metals exploration.

Keystone District

The Keystone district, about 3 miles southeast of the New Rambler district, hosts lode gold mineralization concentrated along northwest-trending shears that cut quartz diorite, quartz-biotite schist, and foliated granodiorite. These shears, subsidiary to the Mullen Creek-Nash Fork shear zone, provide loci for quartz veins and veinlets and copper-gold mineralization with associated epidotization of wallrock. Currey (1965) estimated the total lode gold production from the mines in the Keystone district at about 8,500 ounces.

Sierra Madre / Encampment District

The Encampment mining district in the Sierra Madre mainly produced copper after its discovery in 1874. However, gold and silver were significant byproducts of copper mining. The Encampment (also known as the Grand Encampment) district includes the entire Sierra Madre in south-central Wyoming and extends into Colorado. The district is bisected by the generally east-trending Mullen Creek-Nash Fork shear zone, which is more than one-half mile wide in places. This shear zone forms part of the Cheyenne belt suture (see Principal Metal Districts Map above) that separates the Archean Wyoming Province to the north from cratonized Proterozoic basement of the Colorado Province to the south.

Thick successions of Late Proterozoic metasediments that overlie the Archean basement characterize the northern part of the district, where mineralization is typified by copper-bearing quartzites, pegmatites, quartz veins, and unaniferous metaconglomerate. Middle Proterozoic calc-alkaline metavolcanics intruded by granitic plutons characterize the southern part of the district, where rocks host stratiform volcanogenic sulfides and related mineralization. Fracture-controlled, copper-dominated base metal deposits typify mineralization within the shear zone.

The Ferris-Haggarty mine in the central Sierra Madre was one of the world’s more important copper deposits during the early 1900s. This significant deposit with accessory gold and some silver was developed in a sheared metaconglomerate. The mine produced an estimated 21 million pounds of copper with some byproduct gold and silver. A 1988 estimate of unmined ore included 928,500 tons of 6.5 percent copper containing 116,800 ounces of gold. Current high metals prices have sparked re-evaluation and exploration of the Ferris-Haggarty and adjacent areas.

Amateur prospectors still search the Sierra Madre for gold although it was always secondary to copper in the Encampment district.

Absaroka Mountains

Several large Eocene volcanic centers in the Absaroka Mountains of northwestern Wyoming host significant porphyry copper-silver along with some associated gold. Mining districts in the Absarokas include Kirwin, Stinking Water, Sunlight, and New World (Cook City). Veins associated with the porphyries were first worked in the late 1800s. Large-tonnage, low-grade polymetallic porphyry deposits include disseminated, stockwork, and vein mineralization accompanied by hydrothermal alteration halos. The volcanic centers also exhibit some supergene enriched deposits, replacement deposits within Paleozoic carbonates (in the New World district), and related downstream gold placers. Historically, these placers had little economic importance, however, amateur prospectors continue to work some of them today.

Laramie Mountains

The Silver Crown district, located on the east flank of the Laramie Mountains in southeast Wyoming, was organized in 1879. A mill and smelter operated on a small scale in the district from 1880 to 1900. Structurally controlled copper-gold mineralization parallels regional foliation or occurs in tensional fractures. In the northern part of the district, narrow clay-filled shear zone cataclastics and mylonites host massive, white, copper-bearing quartz veins, and lenses. These are generally excessively narrow with limited tonnage. The southern part of the district hosts low-grade, large-tonnage disseminated copper-gold within granodiorite and quartz monzonite.

Rattlesnake Hills

The Rattlesnake Hills in central Wyoming are a partially exposed fragment of a synformal Archean greenstone belt that was intruded during the Tertiary by alkalic volcanic rocks.

In 1982, the WSGS discovered anomalous gold in the Rattlesnake Hills in pyrite-rich metachert. Hausel (1996) recognized a minimum of three episodes of gold mineralization, including syngenetic stratabound exhalative mineralization, epigenetic mineralization, and disseminated epithermal gold associated with Tertiary volcanic activity.

Exploration in the area by several companies between 1983 and 1993 suggested a large amount of disseminated low-grade gold thought to be more than one million ounces. Exploration also identified some higher-grade stratabound mineralization along with nearby unevaluated targets.

Exploration in the area accelerated after 2008, with efforts by several companies active in the area. The largest, Evolving Gold Corporation, eventually drilled and evaluated 252,000 ft (76,800 m) of core, finding significant gold mineralization.

Evolving Gold sold its property in summer 2015 to GFG Resources Inc., completing the sale in 2016. Exploration activity for gold in the Rattlesnake Hills by GFG Resources continued with an extensive airborne geophysical survey in 2016 and successful drill programs in 2016 and 2017. Exploration activities by GFG Resources are described on their website.

Bear Lodge Mountains District

The Bear Lodge Mountains district in northeastern Wyoming was first prospected in 1875 after the discovery of gold in feldspar porphyry near Warren Peak. Recent exploration in the area has been fostered by both historically known mineralization and by similarities this Tertiary intrusive complex shares with the 30 Ma gold-hosting Cripple Creek igneous complex in Colorado. In addition to gold, mineral values in the Bear Lodge have included rare earth elements (REE), barium, copper, lead, zinc, manganese, niobium, tantalum, thorium, fluorine, and phosphate. Mineralization in the Bear Lodge Mountains includes disseminated, vein, carbonatite, and replacement deposits. The greatest potential for resource development are the REE followed by gold.

Rare Element Resources in October 2014 reported an NI 43-101-compliant (*see footnote on Laramie Mtns page) total high-grade Measured and Indicated (M&I) mineral resource of 15.7 million tonnes (17.3 million tons) averaging 3.11 percent total rare earth oxides at a 1.5 percent cutoff grade, which included M&I resources of 5.4 million tonnes (6 million tons) grading 4.51 percent rare earth oxides at 3 percent cutoff grade.

Gold mineralization occurs within the same large alkaline-igneous complex as the REE mineralization and is comingled with REE in places. On March 15, 2011, Rare Element Resources released an NI 43-101-compliant inferred mineral resource estimate of 26,850 kg (947,000 oz) of gold contained in 69.3 million tonnes (76.4 million tons) averaging 0.42 ppm (0.42 g/tonne; 0.122 oz/ton) using a 0.15 ppm (0.15 g/tonne; 0.004 oz/ton) cutoff grade.

Selected References Related to Metals in Wyoming

Publications relating to metals in Wyoming can be downloaded or purchased from the WSGS Publications Sales and Free Downloads minerals – metals category of the online catalog and from the WSGS Sales Geologic Mapping page.

Blackstone, D.L. Jr., 1988, Traveler’s guide to the geology of Wyoming: Wyoming State Geological Survey Bulletin 67, 130 p.

Blackstone, D.L. Jr., and Hausel, W.D., 1992, Field guide to the Seminoe Mountains: Geological Survey of Wyoming [Wyoming State Geological Survey] Reprint 48, 10 p. (Reprint 1991, Wyoming Geological Association.)

Currey, D.R., 1965, The Keystone gold-copper prospect area, Albany County, Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Preliminary Report 3, 12 p., 1 pl.

Eggler, D.H., Meen, J.K., Welt, F., Dudas, F.O., Furlong, K.P., McCallum, M.E., and Carlson, R.W., 1988, Tectonomagmatism of the Wyoming Province: Colorado School of Mines Quarterly, p. 25–40.

Gersic, J., Peterson, E.K., and Schreiner, R.A., 1990, Appraisal of selected mineral resources of the Black Hills National Forest, South Dakota and Wyoming: U.S. Bureau of Mines Open File Report MLA 5-90, 225 p.

Graff, P.J., 1978, Geology of the lower part of the Early Proterozoic Snowy Range Supergroup, Sierra Madre, Wyoming: Laramie, University of Wyoming, Ph.D. dissertation, 85 p.

Harris, R.E., Hausel, W.D., and Meyer, J.E., 1985, Metallic and indus­trial minerals map of Wyoming: Wyoming State Geological Survey Map Series 14, scale 1:500,000.

Hausel, W.D., 1982, General geologic setting and mineralization of the porphyry copper deposits, Absaroka volcanic plateau, Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Reprint 40, 17 p. (Reprint 1982, Wyoming Geological Association.)

Hausel, W.D., 1982, Ore deposits of Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Preliminary Report 19, 39 p.

Hausel, W.D., 1984, Tour guide to the geology and mining history of the South Pass gold mining district, Fremont County, Wyoming: Wyoming State Geological Survey Public Information Circular 23, folded pamphlet, scale 1:24,000.

Hausel, W.D., 1986, Mineral deposits of the Encampment mining district, Sierra Madre, Wyoming-Colorado: Wyoming State Geological Survey Report of Investigations 37, 31 p.

Hausel, W.D., 1989, The geology of Wyoming’s precious metal lode and placer deposits: Geological Survey of Wyoming [Wyoming State Geological Survey] Bulletin 68, 248 p., 6 pls.

Hausel, W.D., 1991, Economic geology of the South Pass granite-greenstone belt, southern Wind River Range, western Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Report of Investigations 44, 129 p., 2 pls., scale 1:48,000.

Hausel, W.D., 1992, Form, distribution, and geology of gold, platinum, palladium, and silver in Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Reprint 51, 18 p.

Hausel, W.D., 1994, Mining history and geology of some of Wyoming’s metal and gemstone districts and deposits: Geological Survey of Wyoming [Wyoming State Geological Survey] Reprint 56, p. 39–64. (Reprinted 1993, Wyoming Geological Association.)

Hausel, W.D., 1993, Guide to the geology, mining districts and ghost towns of the Medicine Bow Mountains and Snowy Range Scenic Byway: Geological Survey of Wyoming [Wyoming State Geological Survey] Public Information Circular 32, 53 p., 2 pls.

Hausel, W.D., 1994, Geology of the Cooper Hill mining district, Medicine Bow Mountains, southeastern Wyoming: Wyoming State Geological Survey Report of Investigations 49, 22 p., 1 pl., scale 1:1111.

Hausel, W.D., 1994, Economic geology of the Seminoe Mountains mining district, Carbon County, Wyoming: Wyoming State Geological Survey Report of Investigations 50, 31 p., 1 pl., scale 1:24,000.

Hausel, W.D., 1996, Geology and gold mineralization of the Rattlesnake Hills, Granite Mountains, Wyoming: Wyoming State Geological Survey Report of Investigations 52, 28 p., 1 pl., scale 1:24,000.

Hausel, W.D., 1997, Copper, lead, zinc, molybdenum, and other associated metal deposits of Wyoming: Wyoming State Geological Survey Bulletin 70, 229 p., 4 pls.

Hausel, W.D., 2002, Searching for gold in Wyoming: Wyoming State Geological Survey Information Pamphlet 9, 12 p.

Hausel, W.D., 2006, Revised geologic map of the Miners Delight quadrangle, Fremont County, Wyoming: Wyoming State Geological Survey Map Series 38, scale 1:24,000.

Hausel, W.D., 2007, Revised geologic map of the South Pass City quadrangle, Fremont County, Wyoming: Wyoming State Geological Survey Map Series 74, scale 1:24,000.

Hausel, W.D., Edwards, B.R., and Graff, P.J., 1992, Geology and mineralization of the Wyoming Province: Geological Survey of Wyoming [Wyoming State Geological Survey] Reprint 52, 12 p. (Reprinted from Preprint 91-72 presented at the 1991 SME Annual Meeting, Denver, Colo., February 25–28, 1991: Society for Mining, Metallurgy, and Exploration, Inc. [SME].)

Hausel, W.D., Graff, P.J., and Albert, K.G., 1985, Economic geology of the Copper Mountain supracrustal belt, Owl Creek Mountains, Fremont County, Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Report of Investigations 28, 33 p., 3 pls., scale 1:24,000.

Hills, F.A., and Houston, R.S., 1979, Early Proterozoic tectonics of the central Rocky Mountains, North America: University of Wyoming Contributions to Geology, v. 17, no. 2, p. 89-109.

Houston, R.S., 1993, Late Archean and Early Proterozoic geology of southeastern Wyoming in Snoke, A.W., Steidtmann, J.R., and Roberts, S.M., (eds.), Geology of Wyoming: Wyoming State Geological Survey Memoir 5, p.78–116.

Houston, R.S., McCallum, M.E., King, J.S., Ruehr, B.B., Myers, W.G., Orback, C.J., King, J.R., Childers, M.O., Irwin Matus, Currey, D.R., Gries, J.C., Stensrud, H.L., Catanzaro, E.J., Swetnam, M.N., Michalek, D.D., and Blackstone, D.L., Jr., 1978, A regional study of Precambrian age in that part of the Medicine Bow Mountains lying in southeastern Wyoming—With a chapter on the relationship between Precambrian and Laramide structure: Geological Survey of Wyoming [Wyoming State Geological Survey] Memoir 1, 167 p., 35 pls. (Reprinted from 1968.)

Karlstrom, K.E., and Houston, R.S., 1984, The Cheyenne Belt: Analysis of a Proterozoic suture in southern Wyoming: Precambrian Research, v. 25, p. 415–446.

Klein, Terry, 1974, Geology and mineral deposits of the Silver Crown Mining District, Laramie County, Wyoming: Wyoming State Geological Survey Preliminary Report 14, 27 p., scale 1:1,200 and ~ 1:25,344.

Love, J.D., Antweiler, J.C., and Mosier, E.L., 1978, A new look at the origin and volume of the Dickie Springs-Oregon Gulch placer gold at the south end of the Wind River Mountains in Boyd, R.G., Olson, G.M., and Boberg, W.W., (eds.), Resources of the Wind River Basin: Wyoming Geological Association Thirtieth Annual Field Conference Guidebook, p. 379-391.

Love, J.D., and Christiansen, A.C., comps., 1985, Geologic map of Wyoming: U.S. Geological Survey, 3 sheets, scale 1:500,000. (Re-released 2014, Wyoming State Geological Survey).

McCallum, M.E., 1968, The Centennial Ridge gold-platinum district, Albany County, Wyoming: Wyoming State Geological Survey Pre­liminary Report 7, 12 p., scale 1:20,000. (Reprinted 1982.)

McCallum, M.E., and Orback, C.J., 1968, The New Rambler copper-gold-platinum district, Albany and Carbon counties, Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Preliminary Report 8, 12 p., scale ~1:26,400.

Snoke, A.W., Steidtmann, J.R., and Roberts, S.M., eds., 1993, Geology of Wyoming: Geological Survey of Wyoming [Wyoming State Geological Survey] Memoir 5, 2 v., 937 p., 10 pls.

Sutherland, W.M., 2007, Geologic map of the Sundance 30′ x 60′ quadrangle, Crook and Weston counties, Wyoming and Lawrence and Pennington counties, South Dakota: Wyoming State Geological Survey Map Series 78, 26 p., scale 1:100,000.

Sutherland, W.M., 2008, Geologic map of the Devils Tower 30' x 60' quadrangle, Crook County, Wyoming, Lawrence and Butte counties, South Dakota, and Carter County, Montana: Wyoming State Geological Survey Map Series 81, 29 p., scale 1:100,000.

Sutherland, W.M., and Cola, E.C., 2015, Iron Resources of Wyoming: Wyoming State Geological Survey Report of Investigations 67, 92 p.

Sutherland, W.M., and Cola, E.C., 2016, A comprehensive report on rare earth elements in Wyoming: Wyoming State Geological Survey Report of Investigations 71, 137 p.

Sutherland, W.M., and Hausel, W.D., 2003, Geologic Map of the Rattlesnake Hills 30’ x 60’ quadrangle, Fremont and Natrona Counties, Wyoming: Wyoming State Geological Survey Map Series 61, 28 p., scale 1:100,000.

Sutherland, W.M., and Hausel, W.D., 2005, Preliminary geologic map of the Saratoga 30′ x 60′ quadrangle: Wyoming State Geological Survey Open File Report 04-10, 34 p., scale 1:100,000.

Sutherland, W.M., and Hausel, W.D., 2005, Preliminary geologic map of the Keystone quadrangle, Albany and Carbon counties, Wyoming: Wyoming State Geological Survey Open File Report 05-6, 21 p., scale 1:24,000.

Sutherland, W.M., and Hausel, W.D., 2005, Geologic map of the Barlow Gap quadrangle, Natrona County, Wyoming: Wyoming State Geological Survey Map Series 67, scale 1:24,000.

Sutherland, W.M., and Hausel, W.D., 2006, Geologic map of the South Pass 30′ x 60′ quadrangle, Fremont and Sweetwater counties, Wyoming: Wyoming State Geological Survey Map Series 70, 23 p., scale 1:100,000.

Sutherland, W.M., and Worman, B.N., 2013, Preliminary geologic map of the Blackjack Ranch quadrangle, Natrona County, Wyoming: Wyoming State Geological Survey Open File Report 13-3, 24 p., scale 1:24,000.

Ver Ploeg, A.J., and Boyd, C.S., 2007, Geologic map of the Laramie 30′ x 60′ quadrangle, Albany and Laramie counties, Wyoming: Wyoming State Geological Survey Map Series 77, scale 1:100,000.

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