INTRODUCTION
A lack of geochemical data for many metal and gemstone deposits in the Cowboy State requires heavy reliance on host rock geology and geological setting for metallogenic provenance. The data indicates mineral deposits in Wyoming can be grouped into a variety of ore types. Classification of these deposits leads to groups with temporal and/or spatial associations indicating the presence of mineral provinces and districts.
MAGMATIC DEPOSITS
 |
| The Wyoming platinum-palladium-nickel province within the Wyoming Province. |
Other than nickeliferous schists and diamondiferous lamproite, most types of magmatic deposits have been recognized in Wyoming in one form or another. And since a major lamproite field occurs in southwestern Wyoming and high-magnesian schists with peridotitic komatiite composition occur in more than one location, it is possible these latter deposit types may someday be found in Wyoming.
Platinum Group Mineralization
Worldwide, platinum-group metals (PGE) show a strong affinity for large, intracontinental, layered, mafic complexes of tholeiitic affinity. This affinity is demonstrated in southeastern Wyoming where PGE-mineralization is intimately associated with two ~1.8 Ga (age from Houston and others, 1968) Precambrian layered mafic intrusives (Lake Owen and Mullen Creek) in the Medicine Bow Mountains. These layered complexes in the Medicine Bow Mountains intrude Proterozoic schist and gneiss of the Green Mountain terrain. This terrain is interpreted as part of a Precambrian island arc which was accreted to the Wyoming craton about 1,770 Ma. The terrain was intruded by the Mullen Creek mafic complex at about the time of accretion (Loucks and others, 1988).
 |
| Location map of the Lake Owen and Mullen Creek complexes, southeastern Wyoming. |
Typically, PGE metals are found in cyclic cumulus layers. At the Lake Owen intrusive in the Medicine Bow Mountains of Wyoming, anomalous platinum is syngenetic occuring in labradorite-bearing gabbroic norite (Loucks, 1991). In the Mullen Creek mafic complex, however, significant platinum is epigenetic and in hydrothermally altered igneous rock. The effects of deformation on the Lake Owen and Mullen Creek complexes differ greatly (Figure 2a, b).
 |
| Exposed layered complex with anomalous mineralization between the two red flags in trench. |
Nearby Centennial Ridge district exhibits similar evidence for epigenesis in that minor platinum and palladium occur with gold in shear zones in discontinuous mafic intrusives. Elsewhere, platinum nuggets have been recovered from placers of Douglas Creek downstream from the Mullen Creek mafic complex.
 |
| Map of the Medicine Bow Mountains and Sierra Madre showing Lake Owen, Mullen Creek, Centennial Ridge and Puzzler Hill. |
Sporadic mining operations between 1900 and 1918 at the New Rambler mine, produced at least 6,100 tons of copper ore with gold, silver, platinum, and palladium in shear zones (McCallum and Orback, 1968). The U.S. Bureau of Mines (1942) reported mine production included 1.75 million pounds of copper, 170 ounces of gold, 7,350 ounces of silver, 170 ounces of platinum, and 451 ounces of palladium. Actual production of platinum-group metals was greater since 4,000 tons of high-grade copper ore was mined at the turn of the century and sent to the smelter prior to platinum and palladium being discovered in the ore (McCallum and Orback, 1968). Taking this into account, Silver Lake Resources (1985), estimated, platinum and palladium production may have been 910 ounces of platinum and 16,870 ounces of palladium.
 |
| Trench in layered complex, Medicine Bow Mountains, WY |
Loucks and others (1988) recognized more than 21 cyclic units in the Mullen Creek complex. It is not known if syngenetic platinum is associated with these units, but the association of platinum and palladium with shear zones in the layered complex suggests remobilization of the metals from the complex.
Lake Owen mafic complex In contrast to the Mullen Creek complex, the Lake Owen complex is virtually unaffected by deformation and metamorphism. It forms a 20 to 25 mi2 funnel-shaped intrusion tilted 75° on its side exposing a cross-section of at least 16 cyclic units. Vanadiferous titanomagnetite cumulates are persistant in gabbronorite near the tops of some cyclic units (Loucks, 1991).
Cumulus sulfides occur in at least 12 stratigraphic horizons in the complex, with some zones containing elevated gold and platinum ± palladium. Four of the horizons have laterally persistant precious metal anomalies of a few hundred to a few thousand ppb and contain Au-Ag alloys, Pt-arsenides, Pt-Pd tellurides and sulfides associated with disseminated chalcopyrite, pentlandite, pyrrhotite, pyrite, gersdorffite, bornite, millerite, PGE-bearing carrollite (Loucks, 1991). The mineralized zones are generally lensy and spotty and include zones up to 15 feet thick with strike lengths of more than 1 mile.
Centennial Ridge district. North of the Lake Owen complex in the Centennial Ridge district, late 19th Century mine developers cut mafic metaigneous rocks in search of gold associated with platinum-group metals. The mineralization is spotty and in shears and veins. The richest ores were in sulfide-rich zones in mafic mylonites, graphitic fault gouge, and in strongly chloritized zones (McCallum, 1968).
 |
| Magnetite cumulate, Lake Owen complex |
It is apparent some Wyoming platinum is magmatic as well as hydrothermal. Platinum in the Lake Owen complex is clearly magmatic and associated with cumulus layers. In the New Rambler district in the Mullen Creek complex, the platinum is in hydrothermally altered mafic cataclastics. Possibly, the New Rambler ore was leached from discrete mafic rock units by hydrothermal solutions, or remobilized from the deformed layered complex (McCallum and Orback, 1968). Platinum in the Centennial Ridge district is restricted to narrow zones of altered, mafic, metaigneous schist and gneiss and appears to have been remobilized from the mafic country rock (McCallum, 1968).
Titaniferous magnetite
Titaniferous-magnetite occurs within the 350 mi2 anorthosite batholith of the Laramie Mountains, and is present in stratiform layers of the Lake Owen mafic complex of the Medicine Bow Mountains. In addition to titanium, such deposits also have significant iron and anomalous vanadium and chromium.
Titaniferous magnetite in the Laramie Range forms one of the largest deposits of this type in North America. The titaniferous magnetite is distributed in more than 30 separate deposits of disseminated and massive magnetite-ilmenite (Dow, 1961). Many of these occupy the crest of an antiform in the Laramie anorthosite complex (Hagner, 1968).
The deposits consist of lenses of ilmenite, magnetite, and magnetite-ilmenite intergrowths containing minor to accessory olivine, apatite, spinel, mica, and sulfides (pyrrhotite and pyrite) (Reinking and Hagner, 1969). The magnetite and ilmenite occur as discrete grains and as intergrowths and overgrowths. The intergrowths consist of fine interpenetrating networks of ilmenite lamallae along octahedral partings in magnetite. In some samples the titaniferous magnetite partially replaces feldspar and pyroxene indicating the metals to be paragenetically late (Hagner, 1968). Early workers interpreted these deposits as magmatic segregations or injections (Diemer, 1941). Later work by Hagner (1968) considered the titaniferous magnetite to have formed by replacement of the anorthosite along a zone of en echelon fractures. More recently, the titaniferous magnetite has been considered as either a crystal cumulate or the result of magma unmixing (Frost and Simons, 1991) .
Dow (1961) described to types of ore: (1) massive ore and (2) disseminated ore. Chemical analyses of the massive ore show 16 to 23% TiO2. The ore is enriched in vanadium (<1.0% V2O5) and locally enriched in chromium (0.03% to 2.45% Cr2O3) (Diemer, 1941; Hagner, 1968). In addition to massive deposits, disseminated titanomagnetite forms relatively large, low-grade, deposits in the complex (Dow, 1961; Frost and Simons, 1991).
Available resource estimates based on drilling and magnetic surveys indicate reserves of massive titaniferous-magnetite ore in the Laramie anorthosite complex at 30 million tons averaging 45% Fe, 20% TiO2, and 0.64% V2O5 with little or no sulfur, and disseminated ore at 148 million tons averaging 20% Fe, 9.7% TiO2, 0.17% V2O5, and 0.17% S (Dow, 1961). The amount of disseminated ore in the district could be as much as 300 million tons (John Simons, personal communication, 1990). In the 1950s, 1,091,452 tons of titaniferous-magnetite were mined from the anorthosite complex. The ore was used as a heavy mineral concrete in submerged petroleum pipelines in the Gulf Coast.
Chromite & Nickel
The principal chromite deposits of the world are magmatic and associated with >2.0 Ga layered complexes (Edwards and Atkinson, 1986). With the exception of the Lake Owen layered complex, the known Wyoming chromium deposits are associated with serpentinite and ultramafic schist in greenstone belts and related supracrustal fragments. Typically, these deposits occur as weakly anomalous zones to low-grade mineralized zones in the high-MgO rocks. Although no nickel anomalies have been identified in Wyoming, some high MgO and Cr203 serpentinites have whole-rock compositions similar to nickeliferous peridotitic komatiites in Western Australia.
Anomalous chromium is reported in the Casper Mountain, Elmers Rock, South Pass, and the Deer Creek Canyon Archean supracrustal belts. In these terranes, chromite occurs as disseminations, pods, layers, and/or veinlets in serpentinite, talc-tremolite schist, and tremolite-talc-chlorite schist. The chromium is found in chromite (spinel), and in kammererite and wolchonskoite (chromian chlorites). However, silicates (chlorites) are of no economic value. Chrome-rich spinels are also reported in the Lake Owen layered complex (Loucks, 1991).
The known Wyoming chromite deposits are too low grade or too small to be considered economic (Hausel, 1987a). However, some chromite schist mined at Deer Creek in 1908 and during the first world war, yielded grades of 35 to 45% Cr203 (Spencer, 1916; Beckwith, 1955). The chromite-schist on Casper Mountain averages only 2% Cr203, but includes bands of high-grade chromitite that vary from 5 to 25% Cr203. Drilling by the US Bureau of Mines on Casper Mountain identified relatively large low-grade resources (Julihn and Moon, 1945). These chromitites are stratified and associated with serpentinized cumulate peridotite and magnetite-talc-chlorite schist.
The bulk of the world's nickel deposits occur in peridotitic komatiites with >36% MgO. These komatiites are aluminum undepleted with CaO/Al203 ratios of about 1, Al203/TiO2 ratios of nearly 20, and flat chondrite normalized heavy rare earth element (HREE) patterns. They are depleted in light rare earth elements (LREE) and TiO2 (Marston and others, 1981).
Rocks with compositions similar to the Western Australian nickeliferous rocks occur in some Wyoming greenstone belts. In the South Pass greenstone belt, serpentinites and talc-tremolite-chlorite-serpentine schists of the lowermost unit of the greenstone belt vary from 21.15% to 38.1% MgO, 1,700 ppm to 10,100 ppm Cr, and 289 ppm to 2,570 ppm Ni. The CaO/Al2O3 ratios average about 0.6, and the Al203/TiO2 ratios average about 22. These rocks yield some weak Cr2O3 anomalies, and nickel systematically increases with increasing MgO, but is not anomalous in any of the samples collected to date (Hausel, 1991). The available REE contents for these rocks are incomplete. Two ultramafic samples partially analyzed for REE chemistry, possess flat HREE patterns similar to the Australian rocks. But the LREE data are lacking.
Serpentinite from the Seminoe Mountains have compositions consistent with peridotitic komatiite (Klein, 1981). Chemically, they have 25.7 to 36.7% MgO, 1,900 ppm to 6,200 ppm Cr, 810 ppm to 1,600 ppm Ni. CaO/Al203 ratios average 0.41, Al203/TiO2 ratios average 27. Tremolite schists with spinifex texture have 7.01 to 28.4% MgO, 150 to 6,000 ppm Cr, 60 to 1,400 ppm Ni. CaO/Al203 ratios average 0.86 and Al203/TiO2 ratios average 23.
In the Elmers rock greenstone belt, similar ultramafic schists have 11.2 to 28.4% MgO and 713 to 4,900 ppm Cr. CaO/Al203 ratios average 1.25, Al203/TiO2 ratios average 21 (Smaglik, 1987). Five samples were analyzed for REE content and only one sample showed a REE pattern consistent with the Western Australian nickeliferous komatiites. The remaining samples showed LREE enrichment inconsistant with the Western Australian rocks.
Diamondiferous kimberlite
Worldwide, commercial diamond deposits are confined to kimberlites and lamproites in stable shield terranes, and placer deposits presumably derived from these and related mantle rocks (Erlich and Hausel, 2002). Kimberlite and lamproite intrusives have unique nodules, mineral assemblages, and geochemistry indicative of mantle origin. Pressure-temperature estimates based on the chemistry of mineral associations of some ultramafic xenoliths and diamond xenocrysts place the source terrane of the kimberlite intrusives at minimum depths of 120 miles. Phanerozoic mobile belts tend to lack penecontemporaneous diamondiferous kimberlite or lamproite.
Diamondiferous and barren kimberlite, placer diamonds, and lamproite all occur in Wyoming, and the distribution of kimberlitic heavy (satellite) minerals in stream sediments suggest dozens of kimberlites or related intrusives remain undiscovered. Although the known Wyoming kimberlites intrude Proterozic basement rock along the margin of the Wyoming craton, the distribution of kimberlitic satellite minerals suggest that the Colorado-Wyoming kimberlite province may someday extend into the Archean craton.
Geochemically, kimberlite is a potassic ultrabasic igneous rock. Whole-rock analyses of kimberlite from the Colorado-Wyoming region show SiO2 contents of 24.8 to 34.2 %; K20 contents of 0.16 to 1.4%; and Mg0 contents in the range of 12.6 to 31.2 % (Smith and others, 1979). The intrusives are Early Devonian dikes, blows, and diatremes that range from inches wide to the largest known pipe in the region (Sloan 1) with dimensions of 1,800 by 500 feet (McCallum and others, 1977). Kimberlite eruption in Wyoming was enhanced by deep north-northwest fractures developed during the Early Devonian. These intrusives exhibit a variety of textures including porphyries and breccias (McCallum and Mabarak, 1976). Many of the kimberlites, particularly the diamondiferous intrusives, host abundant mantle and lower crustal xenoliths.
.jpg) |
| Aerial view of the Sloan 5 (Evelyn) kimberlite pipe in the Colorado-Wyoming State Line district. The intrusive lies within an open park. A prominent linear fracture along the edge of the pipe is visible in the right-bottom corner of the photo. Mining equipment provide scale. |
The potential for the discovery of additional kimberlite intrusives is high. To date, only modern drainages have been sampled, and these have yielded over a hundred kimberlitic heavy mineral anomalies. Additionally, several prominent magnetic and conductivity anomalies in the State Line district have not been tested.
The lamproites of the Leucite Hills lie within the confines of the Wyoming Province. These are ultrapotassic, basic to ultrabasic, volcanic and volcaniclastic rocks, and include both olivine and leucite lamproites. Geochemically, these have SiO2 contents in the range of 43.0 to 56.5 %; K2O from 3.3 to 12.7 %; and MgO from 5.2 to 11.2 %. The Leucite Hills are relatively young (~1.0 Ma) and form volcanic cones, flows, and necks (Ogden, 1979). A few hundred pounds of both olivine and leucite lamproite have been tested for diamonds by the Wyoming Geological Survey with negative results. Although no diamonds were found, sampling was minimal.
MAGMATIC HYDROTHERMAL DEPOSITS
Hydrothermal alteration accompanies many magmatic metalliferous deposits. Temperature gradients associated with the deposits results in zoned alteration and mineralization. The classic magmatic hydrothermal deposits are porphyry copper deposits and associated vein systems. Spatially associated with some porphyries with high average Au/Ag ratios are large-tonnage, disseminated gold deposits. Porphyries, veins, and disseminated gold mineralization have all been recognized in Wyoming. Volcanogenic massive sulfides, another type of magmatic hydrothermal deposit, have also been recognized.
Porphyry deposits and disseminated gold
.jpg) |
| Mineralized terranes in Wyoming. Tertiary porphyry copper deposits occur in the Absaroka Mountains in northwestern Wyoming, and a Proterozoic gold-copper porphyry in the Silver Crown district in the Laramie Mountains, southeastern, Wyoming |
The Absaroka Mountains form a deeply-dissected Tertiary volcanic plateau of calc-alkaline flows and flow breccias. Some eruptive centers possess classical hydrothermal alteration mineral assemblages and zonation typically seen in many porphyry copper deposits in Alaska, Arizona, New Mexico, and Utah in the US.
In the Kirwin district in the southern Absaroka Mountains, at least three intrusive centers have been recognized (Wilson, 1964). But only the Bald Mountain porphyry has been extensively drilled. This porphyry is surrounded by deuterically altered andesite containing secondary calcite, chlorite, and clay. The andesite gives way to hydrothermally propylitized (quartz-epidote-montmorillonite-calcite-chalcopyrite with chalcopyrite-calcite-quartz veinlets) andesite within 1,500 feet of the intrusive center. Near the intrusive center, phyllically altered assemblages are overprinted by argillic assemblages (quartz-sercite-pyrite-biotite-kaolinite-chlorite- illite/montmorillonite). This phyllic-argillic altered zone encloses a poorly defined potassic zone represented by secondary orthoclase, quartz, and veinlet sulfides (Wilson, 1964; Nowell, 1971).
Zoned mineralization is characteristic of these deposits. Copper-molybdenum-trace gold mineralization surrounds the stocks and gives way to zinc-lead-silver mineralization laterally. Drill hole data show a pyrite-chalcopyrite-molybdenite stockwork at Kirwin with a secondary enriched blanket of chalcocite, digenite, and covellite overlying a portion of the stockworks (Wilson, 1964). Veins in the altered area are chalcopyrite-pyrite-molybdenite-quartz veins (Wilson, 1960). Wilson (1964) reported vein and mine dump samples to assay a trace to 8.58 ppm Au and a trace to 3,835 ppm Ag (111.8 opt). A portion of the ore body was drilled outlining a minimum resource of 70 million tons of 0.75% Cu (Rosenkranz and others, 1979). Estimated contained metals in the porphyry include 1.23 billion lbs of Cu, 121,000 oz of Au, 5.6 million oz of Ag with significant Pb, Zn, Mo, and anomalous Ti (Pay Dirt, 1985) worth more than $1.5 billion (1989 prices).
In the Silver Crown district of the southern Laramie Range, copper is disseminated in Proterozoic quartz monzonite and foliated granodiorite. This porphyry (Copper King) possesses a hydrothermal alteration halo of propylitic and potassic alteration assemblages. Near the old shaft, a zone of intense silicification is expressed by intersecting quartz veins and veinlets. Extending outward from the shaft, is a narrow potassically alter zone has secondary biotite and K-spar. This halo is in turn enclosed by a propylitized zone that includes secondary epidote, chlorite, sulfides, and quartz. The ore body is oxidized to depths of 30 to 150 feet. Below 150 feet, sulfides predominate. The ore body is at least 300 feet wide by 600 to 700 feet long, and is continuous to depths greater than 1,000 feet, and recent exploration identified probable continuation of mineralization under sediment to the east. Drilling by the U.S. Bureau of Mines established a 35-million-ton ore body with average grades of 0.21% Cu and 0.755 ppm Au. A higher grade zone (4.5 million tons averaging 1.51 ppm Au) was later outlined by company drilling (Hausel, 1989). Currently, the deposit is interpreted to host more than 2 million ounces of gold.
Another similar deposit of Proterozoic age was examined in the southern Sierra Madre. This property, Kurtz-Chatterton mine, is surrounded by a well-developed mineralized zone with a 3,500-foot strike length and a minimum width of 600 feet. The mineralized zone is confined to the Sierra Madre granite and contains secondary (?) K-spar, biotite, muscovite, and propylitic mineral assemblages as well as a stockwork. Historic reports indicate some mined ore contained 10 to 20% Cu with gold and silver (Hausel, 1989, p. 156). Hand specimens contain chalcopyrite, cuprite, malachite, and minor chrysocolla.
The Bear Lodge Mountains in the northwestern Black Hills of Wyoming, form a large multiple intrusive complex of alkalic igneous rock ranging in age from 38.0 to 50.0 Ma (Staatz, 1983; Lisenbee, 1985). Staatz (1983) described the complex as a porphyry-type intrusive containing one of the largest, low-grade, disseminated and vein-type REE and thorium deposits in the United States. Disseminated gold mineralization is also associated with feldspathic breccia in the complex (Jenner, 1984). One mineralized zone identified in an elongate intrusive breccia (2,000 by 120 ft) was drilled yielding gold values of 0.343 to 1.72 ppm (Anonymous, 1988). Geologic resource estimates for the intrusive breccia are 8.2 million tons averaging 0.686 ppm gold (Anonymous, 1991).
Twelve to 15 miles southeast of the Bear Lodge Mountains, another Tertiary alkalic intrusive at Mineral Hill shows similar mineralization. Anomalous gold is reported in feldspathic breccia, quartz veins, and in jasperoid (Welch, 1976). Welch (1976) reported breccias with 6 ppm Au and 115 ppm Ag, and jasperoids with 5 ppm Au and 7 ppm Ag, and the author collected quartz vein samples that assayed has high as 130 ppm Au and 330 ppm Ag. Black Buttes, 6 miles to the southwest exhibits epithermal replacement galena, wulfenite, fluorite, and hemimorphite in altered Pahasapa Limestone along a contact with Tertiary alkalic igneous rock (Hausel, 1989). Disseminated gold was also recently discovered in Tertiary alkalics in the Rattlesnake Hills greenstone belt.
Potential for epithermal disseminated gold may also exist in the Rattlesnake Hills of central Wyoming in the vicinity of UT Creek where American Copper and Nickel Company identified several gold anomalies between 1983 and 1987. This area is underlain by Archean supracrustals intruded by Tertiary alkalics and includes some untested jasperoids (Hank Hudspeth, personal communication, 1988). Aspen (Quaking Asp) Mountain along the Rock Springs uplift south of Rock Springs, is another anomalous area with highly silicified sandstones and siltstones covering several square miles. Alunite, kaolinite, localized jasperoid(?), and minor travertine are anomalous. Some weak gold anomalies were recently detected in the silicified zone (Hausel and others, 1992).
Volcanogenic massive sulfides
South of the Mullen Creek-Nash Fork shear zone in the Sierra Madre, volcanogenic zinc-copper-silver massive sulfides occur in epidote-actinolite-magnetite exhalites in differentiated calc-alkaline metarhyolites and meta-andesites of the Green Mountain Formation, in a similar geologic setting to some spectacular massive sulfide deposits in Arizona (Hausel, 2019, 2020). The Wyoming mineralization occurs as stratabound deposits of pyrite, chalcopyrite, and sphalerite, with secondary tenorite and marmatite spatially associated with volcaniclastics with clasts up to several inches in length. Locally, samples of colloform pyrite mantled by chalcopyrite in a magnetite matrix are found near some vent breccias.
Wallrock alteration associated with the massive sulfide mineralization consists of localized sericite-pyrite with broad zones of sausseritization (epidote ± chlorite ± garnet ± calcite ± actinolite) (Conoco Minerals Company, 1982). The geological setting and physical characteristics of these deposits suggests formation by sulfide precipitation in mounds near vents on a Proterozoic seafloor.
.tif) |
| Volcanogenic massive sulfide mineralization exposed in mine rib at the Ferris-Haggarty mine, Sierra Madre, Wyoming. |
The mine operated from 1902 until 1908. Operations terminated following a series of disasters. First the mill at Riverside was partially destroyed by fire in 1906, followed by the destruction of the Riverside smelter by fire in 1907, and a 35% drop in the price of copper in 1908. The ore body was not exhausted and large blocks of 'low-grade' ore (averaging about 5% Cu) remain unmined (Ralph Platt, personal communication, 1988). In addition to the Ferris-Haggarty deposit, similar quartzite-hosted deposits are described at several other locations in the Sierra Madre (Hausel, 1986).
Veins
Quartz veins are common in both volcanic and metamorphic terranes. In Tertiary volcanics, veins are clearly associated with hydrothermal activity and often show classical ore zonation. Some Proterozoic veins in southeastern Wyoming show similar characteristics. In the Archean craton, the association is often not clear, and many veins are undoubtedly related to metamorphic secretion during regional metamorphism and deformation, rather than magmatic hydrothermal processes.
Quartz veins associated with the porphyry stocks of the Absaroka Mountains are zoned. In the Sunlight district, copper-rich veins with trace gold occur near the porphyry center and grade into lead-silver and barren veins away from the stock. Some Proterozic veins are also zoned. Spencer (1904) described precious metal zonation in the Bridger vein of the Sierra Madre, where gold decreased and silver increased with depth.
Several factors may cause ore shoots in hydrothermal veins whether it be host rock chemistry or structure. For example, Schoen (1953) noted a close association of host rock lithology and the type of metals found in the Albion mine. Copper dominated the ore assemblage in meta-limestone, and lead and silver in quartzite. In the Mineral Hill district, the strongly mineralized, near-horizontal, pyritiferous veins of the Treadwell mine are reported to form ore shoots at intersections with a series of vertical fractures.
METAMORPHOGENIC DEPOSITS
During regional metamorphism, fluids released at elevated temperatures and pressures may leach metals from the surrounding rocks and transport them to dilational zones, forming shear zone and vein deposits. Contact metamorphic deposits may result by the intrusion of igneous rock into country rock leading to their recrystallization and replacement at elevated temperatures. These types of deposits are closely related to metamorphic processes.
Shear zone gold
During the initial stages of deformation (D1) of Wyoming's Archean supracrustal belts, regional shortening produced isoclinal folding (F1), regional foliation (S1), and shear zones parallel to S1 and to the F1 fold hinges. Regional metamorphism during D1 liberated fluids from the supracrustal pile which tended to focus in the shear structures. Precipitation of silica synchronous with this early stage of deformation produced quartz veins which were stretched, boudinaged, and sheared parallel to S1. Wallrock alteration associated with gold mineralization is chlorite-carbonate-quartz dominated with minor sericite, microcline, and tourmaline. Most zones are stained by hematite.
At South Pass, gold is closely associated with shear zone structures in a variety of rock types. Bow (1986) showed that there was a close association of gold to carbonated tremolite/actinolite schists with basaltic to peridotitic komatiite compositions, and Spry and McGowan (1989) showed there was also an association with the metagreywacke suite. Additionally, several other rock types in the district host auriferous shears suggesting more than one source rock contributed gold. The variety of source rocks supports the interpretation that the gold originated by metamorphic secretion from the supracrustal pile during a 2.8 Ga regional metamorphic event.
The shears and veins contain trace gold with sporadic ore shoots enriched in gold (Hausel, 1987). Where recognized, fold closures, shear-fault, and shear-shear intersections appear to localize some ore shoots. The Hidden Hand shaft in the Lewiston district was sunk at the intersection of coalescing shears in metagreywacke. The chloritizied-hematized shear intersection is many feet wide with a gold tenor of a trace to 3,100 opt (ounces per ton) (Pfaff, 1978). At the Bullion mine on Strawberry Creek, a shoot was mined at the intersection of a Archean shear and a Laramide(?) tear fault. The localization of this latter shoot suggests gold may have been mobilized synchronous or subsequent to Laramide deformation. My impression is the intersection produced a zone of high permeability that was supergene enriched. Thus, this shoot may be surficial and not extend below ground-water.
Tight to open fold closures control shoots at several mines including the Carissa, Alpine, Diana, Duncan, and Miners Delight. The Duncan shaft was sunk on a steeply plunging drag fold in hornblendic amphibolite. Compared to the adjacent shear splay, the fold closure is more than 10 times enriched in gold. A 2-foot channel sample from the fold nose assayed 33 ppm Au compared to a 37-foot composite chip sample taken in the shear splay that averaged 2.5 ppm Au.
In general, the shears occur as relatively narrow, foliation-parallel zones with brittle and ductile deformation. They are traceable for hundreds of feet to more than 11,000 feet along strike (Hausel, 1991) and are continuous to minimum depths of at least 900 feet based on drilling (deQuadros, 1989).
Later mineralizing episodes occurred after the development of the auriferous shear zones. This is clearly seen at South Pass where a swarm of copper-gold-silver quartz veins cut the earlier auriferous shears. These veins occur in greater frequency near the margins of the greenstone belt, and have also been identified in the adjacent granodiorite plutons, implying a possible relationship to the cratonization event that produced the major 2.6 Ga batholiths along the margin of the greenstone belt.
Veins
Veins related to metamorphic processes are characteristically not zoned. The Mary Ellen vein (Archean) in the South Pass-Atlantic City district along the northwestern flank of the South Pass greenstone belt is a crosscutting vein hosted by metatonalite porphyry. This milky quartz vein is dominated by gold with uncommon pyrite. Gold values are found to increase where the vein pinches, and no mineralogical zonation has been noted. Veins along the Sweetwater River in the Lewiston district to the southeast parallel foliation and contain argentiferous arsenopyrite and minor gold. Again, no mineralogical zonation was noted.
In the Seminoe Mountains greenstone belt, gold-chalcopyrite-pyrite-quartz veins occur in a 1/4-mile diameter chlorite-calcite-sulfide alteration haloe in metagabbro and metabasalt (Klein, 1981). The quartz veins develop shoots at vein intersections and in fold closures.
Skarns
The intrusion of rock by magma and its associated hydrothermal fluids often leads to replacement and recrystallization. When such hot mineralizing fluids contact carbonates, the resulting replacements (skarns) can be profound. These contact metamorphic deposits, until very recently, have been essentially unknown in Wyoming.
Some localized replacement lead-zinc-silver mineralization has been described in the Black Buttes area of the Black Hills. Mapping in the Cooper Hill district of the Medicine Bow mountains, led to the discovery of skarns in meta-limestone of Proterozoic age associated with gabbrioic and basaltic intrusives (Hausel and others, 1992). These include (1) garnet (hydrogrossular), epidote, actinolite, chlorite, idocrase(?), calcite, limonite, (±) magnetite hornfels, (2) epidote, pyrite, calcite, quartz hornfels, (3) magnetite hornfels, (4) calcite, epidote, actinolite, pyrite, magnetite marble, (5) actinolite, calcite, quartz, chlorite, (±) chalcopyrite hornfels, (6) tremolite, calcite, quartz marble, and (7) uvarovite-magnetite-calcite hornfels.
STRATIFORM AND STRATABOUND DEPOSITS OF SEDIMENTARY AFFILIATION
Stratiform and stratbound deposits of sedimentary affiliation include some of the largest known metalliferous deposits in Wyoming. The source of the metals of these deposits is not always clear. Typically, the statiform deposits contain mineralization that is concordant to stratification, and the stratabound deposits are confined stratigraphically, and mineralization can be either concondant or disconcordant to stratification.
Copper-silver-zinc redbeds
Copper-silver-zinc redbed mineralizaton is widespread in the thrust belt of western Wyoming (Hausel and Harris, 1983). Many of these deposits and occurrences lie along the contact of the Nugget Sandstone (Triassic-Jurassic) and the overlying Gypsum Spring Member (Jurassic) of the Twin Creek Limestone (Boberg, 1986). Some deposits show evidence of both structural and stratigraphic control. The redbeds are bleached indicating the mineralizing fluids were reducing.
.JPG) |
| The author stands next to the mineralized mine rib within the Griggs mine, Overthrust belt, Wyoming. |
Ore shipped from the district between 1914 and 1920, and ore recovered from the mine in 1942 averaged 3.5% Cu and 254 ppm Ag (Allen, 1942). Samples collected by Love and Antweiler (1973) contained 180 ppm 6.7% Cu, a trace to 0.5% Pb, 26 ppm 3.2% Zn, and a trace to 1,200 ppm Ag.
Banded iron formation
Significant resources of Archean banded iron formation (BIF) occur in the Copper Mountain, South Pass, and Seminoe Mountains supracrustal belts, and additional BIF is found in the Barlow Gap, Sellers Mountain, and Elmers Rock belts. In the Hartville uplift of southeastern Wyoming, giant resources of hematite schist occur in a eugeoclinal belt of Archean (?) age.
%2010-42-15-871.jpg) |
| Folded banded iron formation from South Pass greenstone belt, Wyoming has alternating bands of black magnetite, and gray quartz |
Sulfides are uncommon in the BIF, but locally may form up to 5% of the rock. The sulfides (pyrite with subordinate chalcopyrite) are principally stratiform with some crosscutting veinlets. The BIF has been structurally thicken by internal folding and plication and by repetition by slippage along faults.
Gold distribution has been incompletely examined in the BIF. Available records indicate one mine was developed in a crosscutting quartz vein adjacent to BIF at the Atlantic City iron mine. The ore averaged 2.06 ppm Au (Bayley, 1963). Elsewhere, samples of BIF have assayed as high as 1.1 ppm Au with some quartz stingers containing 0.4 ppm Au (Hausel, 1991).
BIF in the Copper Mountain district crops out as four, relatively continuous, narrow beds along an 8-mile strike. These rocks contain both quartz and magnetite but also have abundant grunerite (Hausel and others, 1985). Near the center of the district, a shaft was sunk (McGraw mine) in copper-stained magnetite-rich iron formation. No production history is available for the mine, but it is suspected the shaft was sunk to test a nearby cupriferous strike vein.
BIF in the Seminoe Mountains greenstone belt forms a large resource in the Bradley Peak thrust sheet (Blackstone, 1965). The iron formation is intercalated in metasediments, follows schistosity in metabasalt and metagabbro, and occurs as interflow sediments between basaltic komatiite flows. Locally, the BIF is structurally thickened producing a giant iron ore resource. Harrer (1966) indicated the north slope of Bradley Peak contains a resource of 100 million tons. The iron deposits continue beyond the north slope, suggesting the total resource to be much greater. Chemical analyses of the Seminoe BIF give iron contents of 28.7% to 68.7% Fe (Harrer, 1966). Localized gold and silver anomalies have been detected (Hausel, 1989).
BIF in the Barlow Gap supracrustal belt of the Granite Mountains is found in a metavolcanic-metasedimentary sequence intruded by Tertiary alkalics. Gold anomalies have been identified in a variety of rock types in this area (John T. Ray, personal communication, 1991) including iron formation (Bob Kellie, personal communication), and metachert (Hausel, 1989).
Iron deposits in the Hartville uplift were commercially mined until 1981. About 45 million tons of ore were mined from the Sunrise deposit, where the ore occurs as hematite schist in the Silver Springs Schist (Snyder and others, 1989). Gold anomalies have also been detected in some hematite schists in the Hartville uplift (Woodfill, 1987).
PLACER DEPOSITS
One significant untapped resource in Wyoming is paleoplacer deposits along with placers. Paleoplacers are recognized in rocks of Precambrian, Cambrian, Jurassic, Cretaceous, and Tertiary age. Precambrian conglomerates of Archean and Proterozoic age exhibit similarities to Blind River, Canada and Witwatersrand, South Africa uranium and gold deposits (Paul Graff, pers. comm). Cambrian conglomerates exhibit similarities to the Deadwood, South Dakota gold deposits, and Wyoming's auriferous Cretaceous and Tertiary conglomerates may oneday yield commercial gold. But incredibly, these remain mostly unexplored.
Modern placers have yielded some gold and other valuable heavy minerals in the past. These range from relatively restricted occurrences to larger deposits.
Gold paleoplacers
To date, production from paleoplacers and their associated reworked placers, has been minimal, although the shear volume of paleoplacer material implies these could become important sources of gold and other heavy minerals.
 |
| Precambrian, stretched pebble conglomerate, Medicine Bow Mountains. Such ancient, metamorphosed Wyoming paleoplacers yielded anomalous and isolated uranium, thorium and gold. One company even reported diamonds. |
Cambrian paleoplacers are described at several locations in the state. At South Pass, Flathead Sandstone conglomerates were explored for gold, although the paleocurrent directions (into the greenstone belt) indicate limited gold content. In the Bald Mountain district of the Bighorn Mountains, low-grade gold and monazite paleoplacers form relatively large resources. Several other localities in the State, the Flathead Sandstone has yielded anomalous monazite, gold, or other heavy minerals. One similar unexplored conglomerate is the Fountain Formation(?) conglomerate of Pennsylvanian age. In southeastern Wyoming near the State Line district, native copper and copper carbonate were discovered in this conglomerate prior to 1906. The conglomerate remains unexplored for other heavy minerals.
Tertiary paleoplacers are abundant in the State. These consist of fanglomerate and fluvial conglomerates that locally include giant boulders eroded from the nearby uplifts. The more highly mineralized conglomerates lie adjacent to greenstone belts. For example, the South Pass greenstone belt is flanked by two giant paleoplacers known as the Twin Creek (Antweiler and others, 1980) and Oregon Buttes paleoplacers (Love and others, 1978; Hausel and Love, 1991), and large areas of the greenstone belt are also overlain by additional paleoplacers. One of these was recently explored by magnetic surveys and trenching revealing a complex braided paleo-channel with gold values (Fred Groth, personal communication, 1989).
Titaniferous black sandstone
Titaniferous black sandstone (Late Cretaceous) is relatively widespread. These paleobeach sands occur primarily in the Mesaverde Formation. The black sandstones are enriched in heavy mineral suites which include anatase, sphene, rutile, ilmenite, titanomagnetite, magnetite, monazite, zircon, and gold. Minerals of potential economic value include the titanium-bearing assemblage of sphene, rutile, anatase, ilmenite, and titanomagnetite; zircon for zirconium and hafnium; monazite for rare earth metals; a niobium-bearing opaque; and gold (Houston and Murphy, 1962, 1970).
The deposits differ greatly in grades and size. The Grass Creek deposit in the Bighorn Basin is the largest high-grade deposit in Wyoming (Houston and Murphy, 1962) and includes significant resources of titanium (averages 16% TiO2), and zircon (3 million tons averaging 4.8% ZrSi04) (William Graves, personal communication, 1990). Some younger deposits (i.e., Sheep Mountain in southeastern Wyoming and deposits in northeastern Wyoming) contain a similar suite of heavy minerals and are also anomalous in gold (Madsen, 1978). Values as high as 1.3 ppm Au have been reported by Houston and Murphy (1970) and 1.7 ppm by William Graves (personal communication, 1990).
Modern placers
Gold tenors of modern placers in the state range from a trace to more than an 1.0 oz/yd3. Generally, the commercial placers average about 0.01 oz/yd3, although exceptional placers have averaged 0.1 oz/yd3.
 |
| A 24-ounce (also reported as 34 ounces) nugget recovered in Rock Creek, South Pass, Wyoming |
Nuggets recovered from Wyoming placers include walnut-size nuggets from Mineral Hill, Douglas Creek, and the South Pass greenstone belt. The largest nugget found in Wyoming may have been a fist-size specimen of mixed rock with 24-ounces (34 ounces?) of gold reported to have been found on Rock Creek in the South Pass area prior to 1905. Another interesting specimen found in the same area consisted of country rock with an estimated 630 ounces of gold. Several other nuggets ranging in weight up to 5-ounces have also been described (Hausel, 1991). Most nuggets in the State are rounded typical of detrital transport, although Day and others (1988) report slivers and hairs of gold from gravels in the Lewiston district. In addition to placer gold, other heavy minerals of potential value have been identified in Wyoming placers (Table 1).
Table 1. Predominant heavy minerals reported in some modern placers in Wyoming.
|
Gold placer or district |
Heavy Minerals |
|
Lewiston district |
Gold, scheelite, cassiterite |
|
South Pass-Atlantic City district |
Gold, scheelite, cassiterite, chromite |
|
Crows Nest |
Gold, scheelite. |
|
Mineral Hill district |
Gold, cassiterite, tantalite |
|
Douglas Creek |
Gold, platinum, palladium |
|
Cortez Creek |
Gold, diamond |
|
Clarks Camp |
Gold, monazite |
|
Bald Mountain |
Gold, monazite |
Nugget Creek Silver, gold
Muddy Creek Monazite
A study of sand and gravel deposits for gold occurrences resulted in the identification of gold colors at many of the locations sampled (Hausel and others, 1992). This widespead occurrence of gold could lead to the recovery of by-product gold from some sand and gravel operations.
GEMSTONES
Few gemstones were recognized in Wyoming prior to 1975 - essentially, the only gems and semi-precious gems known in the state was jade, with a few scattered occurrences of agate and jasper. But from 1977 to 2007, hundreds of anomalies were recognized and the data supports the presence of many more undiscovered deposits (Hausel, 2014). Prior to 1975, no one bothered to look for gemstones other than the jade found in the vicinity of Crooks Gap near Jeffrey City.
Gemstones are found in a variety of geologic settings and may be the result of crystal growth and/or replacement during regional metamorphism producing jade, sapphire, or ruby; magma cooling producing peridote or aquamarine phenocrysts or megacrysts; partial melting at great depths where diamond xenocrysts may be captured and brought to the earth's surface; or just simply low temperature silica replacement of fossils and wood at the earth's surface. In the past, the State has been noted for its abundant and high-quality jade and varieties of chalcedony, although a variety of gemstones and semi-precious and lapidary stones have been found in Wyoming.
Jade
Wyoming jade (nephrite) is a monomineralic rock composed of calcium- and magnesium-rich amphibole. Nephrite has been found at a number of localities in central Wyoming including the Prospect Mountains of the southern Wind River Mountains, the Granite Mountains, the Seminoe Mountains, the northern Laramie Mountains, and has also been found in fanglomerates derived from these areas. The jade recovered in past years has included material ranging from the poorest quality black jade to some of the highest quality apple green jade ever found in the world.
.JPG) |
| Emerald green jade with crystalline quartz, Crooks Gap Wyoming. |
Field, chemical, and petrographic data suggest nephrite was formed by metasomatic alteration of amphibolite. Sherer (1969) suggested the following reaction in the presence of water: hornblende » prismatic actinolite » fibrous actinolite (nephrite) » chlorite + talc » serpentine.
Diamond
Diamonds recovered from the Colorado-Wyoming district, McCallum and others (1979) reported the majority of diamonds were aggregates, octahedra, and transitional octahedra-dodecahedra crystals. Subordinate morphologies include macles, irregulars, flattened dodecahedra, and dodecahedra. Octahedra and macles were the principal growth forms. Dodecahedra forms evolved from octahedra.
.jpg) |
| Many kimberlite, lamproite, lamprophyre and diamond indicator minerals have been identified in Colorado, Kansas, Montana, and Wyoming |
Research by Colorado State University, the Wyoming Geological Survey, and others, have identified hundreds of anomalies throughout Colorado, Kansas, Montana, and Wyoming. Only a small number of these have been examined in detail, and some remain unexplored. Some of the kimberlites explored to date, have yielded gem-quality diamonds, chromian diopside, almandine, pyrope and spessartine garnet, as well as many rare and unique lower crustal and upper mantle nodules (Hausel, 2008).
Other gemstones
Rubies and sapphires are described in Wyoming, and some have yielded attractive gems, but most deposits enclose corundum, and have a majority of industrial material with lessor ruby and/or sapphire (Hausel, 2003, 2002).
Aquamarine beryl-bearing pegmatites are described from the Copper Mountain district of the Owl Creek Mountains. And rare aquamarine is also found in pegmatite at Anderson Ridge area of South Pass. One translucent, light-blue, prismatic, hexagonal aquamarine from the Anderson Ridge at South Pass weighed more than a thousand carats (Sutherland, 1990).
Pyrope garnet and chromian diopside are found in ant hills in the Green River Basin. These minerals produce attractive faceted stones. The gems are found in anthills, soil, conglomerate, and in uncommon lamprophyre diatremes at Cedar Mountain near the Utah border (McCandless and others, 1995; Hausel and others, 1999).
Beautiful high-quality amethyst and smoky quartz has been recovered from open-space fractures in granite south of the Battle Lake area in the Sierra Madre (Ralph E. Platt, personal communication, 1989). Amethyst and drusy lavendar chalcedony was also recently found at the Artic mine in the Mineral Hill district (Sutherland, 1990).
Some other attractive gemstones found in Wyoming include labradorite in the Buttes area of the Laramie Range anorthosite complex which produces a 'fire' similar to opal. Small amounts of poor quality opal and some gem quality amber are found in the Absaroka Mountains, as well as enormous amounts of opal and agate found in the Cedar Rim area near Riverton. Peridot crystals, up to 1 to 2 cm are found in some of the olivine lamproites in the Leucite Hills.
The relatively recent discoveries of at least two, world-class iolite (gem-quality cordierite) deposits in the Laramie Mountains, are impressive. One deposit was explored in 1949 as a potential source for heat-shock resistant material and determined to include at least 500,000 short tons of cordierite (Newhouse and Hagner, 1949). Decades later, Hausel recognized gem-quality iolite and suggested that the deposit could potentially include a resource in trillions of carats based on the 1949 study! Another iolite deposit, Grizzly Creek, encloses giant gemstones weighing in the millions of carats.
During studies of gemstones and lapidary materials in Wyoming, Hausel (2014) and Hausel and Sutherland (2000) identified dozens of gem occurrences and deposits in the cowboy state that include agate jasper, peridot, iolite, apatite, garnet, etc. Because of research by both Hausel and Sutherland, Wyoming is now recognized as having the most diversified assortment of gemstones and the largest quantity of gemstones compared to any other state in the US. This research identified dozens of anomalies that remain unexplored, but one day, should lead to additional discoveries!
ACKNOWLEDGEMENTS
W. W. Boberg and Robert S. Houston reviewed this manuscript and provided helpful suggestions and comments. I very much appreciate their comments and suggestions and I am indebted to both Bill and Bob for helping me clarify some of my ideas. Sheila Robert's editorial review greatly improved the organization of the paper. Thanks again Sheila for your help.
REFERENCES
Allen, F.S.,1942, Letter to the Board of Directors of the Polaris Mining Company: Geological Survey of Wyoming mineral files (unpublished), 3 p.
Anonymous, 1988, International Curator Resources Ltd. annual report: Denver Colorado, 4 p.
Anonymous, 1991, Exploration roundup: Engineering and Mining Journal, April
Antweiler, J.C., Love, J.D., Mosier, E.L., and Campbell, W.C., 1980, Oliogocene gold-bearing conglomerate southeast margin of Wind River Mountains, Wyoming: Wyoming Geological Association 32nd Annual Field Conference Guidebook, p. 223-237.
Bayley, R.W.,1963, Preliminary report on Precambrian iron deposits near Atlantic City, Wyoming: U.S. Geological Survey Bulletin 1142-C, 23 p.
Bayley, R.W.,1968, Ore deposits of the Atlantic City district, Fremont County, Wyoming in J.D. Ridge, editor, Ore deposits of the United States, 1933-1967: AIME, New York, p. 589-604.
Beckwith, R.H.,1955, Chromite in Wyoming: Geological Survey of Wyoming, Mineral Report MR55-8 (unpublished), 3 p.
Beeler, H.C.,1905, Mining in the Grand Encampment copper district, Carbon and Albany counties, Wyoming: Office of the State Geologist, Cheyenne, Wyoming, 31 p.
Blackstone, D.L., Jr., 1965, Gravity thrusting in the Bradley Peak-Seminoe Dam quadrangles, Carbon County, Wyoming and relationships to the Seminoe iron deposits: Geological Survey of Wyoming Preliminry Report 6, 13 p.
Boberg, W.W.,1986, Lake Alice copper district, Lincoln County, Wyoming, in Sheila Roberts, editor, Metallic and nonmetallic deposits of Wyoming and adjacent areas, 1983 conference proceedings: Geological Survey of Wyoming Public Information Circular 25, p. 54-55.
Bow, C.S., 1986, Structural and lithologic controls on greywacke-hosted gold mineralization within the Sweetwater district, Wyoming USA, in L.D. Ayres, P.C. Thurston, K.D. Card, and W. Weber, editors, Turbidite-hosted gold deposits: Geological Association of Canada Special Paper 32, p.107-113.
Bowdin, H., 1918, Report on Williams-Luman copper mine at DePass, Wyoming: Geological Survey of Wyoming Mineral Report MR18-1 (unpublished), 7 p.
Conoco Minerals Company,1982, Project summary report on the Fletcher and Huston Parks massive sulfides: Geological Survey on Wyoming files (unpublished), 110 p.
deQuadros, A.M.,1989, Report on the diamond drill program (July-August 1989) at the Carissa mine property, South Pass City, Fremont County, Wyoming: Consolidated McKinney Resources Ltd, Vancouver, B.C., 76 p.
Diemer, R.A.,1941, Titaniferous magnetite deposits of the Laramie Range, Wyoming: Geological Survey of Wyoming Bulletin 31, 23 p.
Dow, V.T.,1961, Magnetite and ilmenite resources, Iron Mountain area, Albany County, Wyoming: U.S. Bureau of Mines Information Circular 8037, 35 p.
Edwards, R., and Atkinson, K.,1986, Ore deposit geology: Chapman and Hall, London, 466 p.
Erlich, E.I., and Hausel, W.D., 2002, Diamond Deposits: Origin, Exploration, and History of Discovery: Society for Mining, Metallurgy, and Exploration, 374 p.
Fisher, F. S., 1981, Controls and characteristics of metallic mineral deposits in the southern Absaroka Mountains, Wyoming: Montana Geological Society 1981 Field Conference Guidebook, p. 343-348.
Frost, B.R., and Simons, J.P., 1991, Fe-Ti oxide deposits of the Laramie anorthosite complex: their geology and proposed economic utilization, in B.R. Frost and Sheila Roberts, editors, Mineral resources of Wyoming, Wyoming Geological Association 42nd Field Conference Guidebook, p. 41-48.
Gold, D.P., 1984, A diamond exploration philosophy for the 1980s: Pennsylvania State University Earth and Mineral Sciences, v. 53, no. 4, p. 37-42.
Hagner, A.F.,1968, The titaniferous magnetite deposit at Iron Mountain, Wyoming, in J.D. Ridge, editor, Ore Deposits of the United States, 1933-1967: AIME, New York, p. 666-680.
Harrer, C.M., 1966, Wyoming iron-ore deposits: U.S. Bureau of Mines Information Circular 8315, 112 p.
Hausel, W.D.,1982, General geologic setting and mineralization of the porphyry copper deposits, Absaroka Volcanic Plateau, Wyoming: Wyoming Geologial Association 33rd Annual Field Conference Guidebook, p. 297- 313.
Hausel,W.D.,1986, Mineral deposits of the Encampment mining district, Sierra Madre, Wyoming-Colorado: Geological Survey of Wyoming Report of Investigations 37, 31 p.
Hausel,W.D.,1987, Structural control of Archean gold mineralization within the South Pass greenstone terrain, Wyoming (USA), in R.W. Hurst, T.E. Davis, and S.S. Augustithis, editors, The practical application of trace elements and isotopes to environmental biogeochemistry and mineral resources evaluation: Theophrastus Publication, Athens, Greece, p.199-216.
Hausel,W.D., 1989, The geology of Wyomings precious metal lode and placer deposits: Geological Survey of Wyoming Bulletin 68, 248 p.
Hausel, W.D., 1991, Economic geology of the South Pass granite-greenstone belt, southern Wind River Range, Wyoming: Geological Survey of Wyoming Report of Investigations 44, 129 p.
Hausel, W.D., 1998, Diamonds & Mantle Source Rocks in the Wyoming Craton with Discussions of Other US Occurrences. WGS Report of Inv 53, 93 p.
Hausel, W.D., 2000, The Wyoming platinum-palladium-nickel province: geology and mineralization: WGA Field Conference Guidebook, p. 15-27.
Hausel, W.D., 2002, Iolite and corundum in Wyoming: Gems & Gemology, v. 37, no. 4, p. 336-337.
Hausel, W.D., 2003, Cordierite (iolite) and corundum (sapphire, ruby) – Potential Wyoming gemstones: Proceedings of the 39th Forum on the Geology of Industrial Minerals, May 18th-24th (2003). Nevada Bureau of Mines and Geology Special Publication 33, p. 130-138.
Hausel, W.D., 2004, Peridot in the Leucite Hills: CMJ Prospecting and Mining Journal.
Hausel, W.D., 2005, Geologists Locate Giant Gemstones: CMJ Prospecting and Mining Journal, v. 74, no. 7, p. 7-9.
Hausel, W. D., 2009, The Wyoming Platinum-Palladium-Nickel Province: Metal Trends Forum, Germany, v.1, p. 12-18.
Hausel, W.D., 2007, Diamond deposits of the North American Craton: Colorado Geological Survey Industrial Minerals Forum, 48 p.
Hausel, W.D., 2007, Gemstones of Wyoming - Recent discoveries: Colorado Geological Survey Industrial Minerals Forum, 12 p.
Hausel, W.D., 2008, Diamond Deposits of the North American Craton in Woods, A., & Lawlor, J., eds, Topics in Wyoming Geology, WGA Guidebk. p. 103-138.
Hausel, W.D., 2008, Geology and Gemstone Deposits - Exploration Models for Wyoming in Woods, A. & Lawlor, J., eds., Topics in Wyoming Geology, WGA Guidebook, p. 77-101.
Hausel, W.D., 2008, Significant gold mineralization-Wyoming examples in Woods, A., and Lawlor, J., eds., Topics of Wyoming Geology, WGA Guidebk, p. 59-76.
Hausel, W.D., 2014, A Guide to Finding Gemstones, Gold, Minerals and Rocks: Createspace, 369 p.
Hausel, W.D., 2019, Gold in Arizona - A Prospector’s Guide: GemHunter Books, 390 p.
Hausel, W.D., 2020, Gold in Arizona (Kindle version), Amazon.
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 Report of Investigations 28, 33 p.
Hausel, W.D., and Harris, R.E., 1983, Metallogeny of some Wyoming deposits: Colorado Mining Association 1983 Mining Yearbook, p.46-63.
Hausel, W.D., and Love, J.D., 1991, Field guide to the geology and mineralization of the South Pass region, Wind River Range, Wyoming, in B.R. Frost and Sheila Roberts, editors, Mineral resources of Wyoming, Wyoming Geological Association 42nd Field Conference Guidebook, p. 181-200.
Hausel, W.D., and Sutherland, W.M., 2000, Gemstones & Other Unique Minerals & Rocks of Wyoming - A Field Guide for Collectors: WGS Bulletin 71, 268 p.
Hausel, W.D., and Sutherland, W.M., 2006, World Gemstones: Geology, Mineralogy, Gemology & Exploration: WGS Mineral Report MR06-1, 363 p.
Hausel, W.D., Marlatt, G., and Neilson, E., 1992, Reconnaissance geochemical and geological studies on the precious metal and gemstones potential of southern Wyoming: Geological Survey of Wyoming Open File Report, in preparation.
Hausel, W.D., Kucera, R.E., McCandless, T.E., and Gregory, R.W., 1999, Mantle-derived breccia pipes in the southern Green River Basin of Wyoming (USA): In J.J. Guerney et al (editors) Proceedings of the 7th International Kimberlite Conference, Capetown, South Africa. p. 348-352.
Hausel, W.D., Love, C.M., and Sutherland, W.M., 1995, Field Guide to the geology and volcanology to the Leucite Hills, Green River Basin, Wyoming: WGA Road Logs to the Resources of Southwestern Wyoming, p. 45-53.
Houston, R.S., and Karlstrom, K.E.,1979, Uranium-bearing quartz pebble conglomerates-exploration model and United States resource potential: U.S. Department of Energy Open File Report GJBX-1(80), 510 p.
Houston, R.S., Karlstrom, K.E., and Graff, P.J.,1979, Progress report on the study of radioactive quartz-pebble conglomerate of the Medicine Bow Mountains and Sierra Madre, southeastern Wyoming: U.S. Geological Survey Open File Report 79-1131, 41 p.
Houston, R.S., and Murphy, J.R.,1962, Titaniferous black sandstone deposits of Wyoming: Geological Survey of Wyoming Bulletin 49, 120 p.
Houston, R.S., and Murphy, J.R.,1970, Fossil beach placers in sandstones of Late Cretaceous age in Wyoming and other Rocky Mountain states: Wyoming Geological Association 22nd Annual Field Conference Guidebook, p. 241-249.
Hurlbut, C.S., and Switzer, G.S.,1979, Gemology: John Wiley & Sons, New York, 243 p.
Jenner, G.A., 1984, Tertiary alkalic igneous activity, potassic fenitization, carbonatitic magmatism, and hydrothermal activity in the central and southeastern Bear Lodge Mountains, Crook County, Wyoming: M.S. thesis, University of North Dakota, Grand Forks, 232 p.
Julian, C.E., and Moon, L.B.,1945, Summary of the Bureau of Mines exploration projects on deposits of raw material resources for steel production: U.S. Bureau of Mines Report of Investigations 3801, 55 p.
Klein, T.L.,1981, The geology and geochemistry of the sulfide deposits of the Seminoe district, Carbon County, Wyoming: PhD thesis, Colorado School of Mines, Golden, Colorado, 232 p.
Lisenbee, A.L.,1985, Tectonic map of the Black Hills uplift, Montana, Wyoming, and South Dakota: Geological Survey of Wyoming Map Series 13, scale 1:250,000.
Loose, S.A.,1988, Sedimentary facies, ore mineralogy, and paragenesis of the Lake Alice Cu-Ag-Pb-Zn district in the Wyoming Overthrust Belt: M.S.thesis, University of Wyoming, 177 p.
Loose, S.A., and Boberg, W.W.,1987, Sedimentary facies control on mineralization at the Lake Alice district in the Wyoming Overthrust Belt: Wyoming Geological Association 38th Annual Conference Guidebook, p. 309-327.
Loucks, R.R.,1991, Platinum-gold and vanadiferous magnetite mineralization in the Early Proterozoic Lake Owen layered mafic intrusion, Medicine Bow Mountains, Wyoming, in B.R. Frost and Sheila Roberts, editors, Mineral resources of Wyoming, Wyoming Geological Association 42nd Field Conference Guidebook, p. 37-38.
Loucks, R.R., Premo, W.R., and Snyder, G.L.,1988, Petrology, structure, and age of the Mullen Creek layered mafic complex and age of arc accretion, Medicine Bow Mountains, Wyoming: Geological Society of America Abstracts with Programs, v. 20, p. A73.
Love, J.D., and Antweiler, J.C., 1973, Copper, silver, and zinc in the Nugget Sandstone, western Wyoming: Wyoming Geological Association 25th Annual Field Conference Guidebook, p. 139-147.
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: Wyoming Geological Association 30th Annual Field Conference Guidebook, p. 379-391.
Madsen, M., 1978, A statistical analysis of heavy mineral variations in upper Cretaceous black sandstone deposits of the Rocky Mountain states: M.S.thesis, University of Wyoming, 138 p.
Marston, R.J., Groves, D.I., Hudson, D.R., and Ross, J.R.,1981, Nickel sulfide deposits in Western Australia: a review: Economic Geology, v.76, p. 1330-1363.
McCallum, M.E.,1968, The Centennial Ridge gold-platinum district, Albany County, Wyoming: Geological Survey of Wyoming Preliminary Report 7, 12 p.
McCallum, M.E., Eggler, D.H., Coopersmith, H.G., Smith, C.B., and Mabarak, C.D., 1977, Field guide to the Colorado-Wyoming State Line District: Colorado State University Department of Earth Resources, Second International Kimberlite Conference, 23 p.
McCallum, M.E., Loucks, R.R., Carlson, R.R., Cooley, E.F., and Doerge, T.A., 1975, Platinum metals associated with hydrothermal copper ores of the New Rambler mine, Medicine Bow Mountains, Wyoming: Economic Geology v.71, p.1429-1450.
McCallum, M.E., and Mabarak, C.D., 1976, Diamond in State-Line kimberlite diatrenes, Albany County, Wyoming, Larimer County, Colorado: Geological Survey of Wyoming Report of Investigations 12, 36 p.
McCallum, M.E., Mabarak, C.D., and Coopersmith, H.G.,1979, Diamonds from kimberlites in the Colorado-Wyoming State Line District, in F.R. Boyd and H.O.A. Meyer, editors, Kimberlites, diatremes, and diamonds: their geology, petrology, and geochemistry: American Geophysical Union, Washington D.C., p. 42-58.
McCallum, M.E., and Orback, C.J., 1968, The New Rambler copper-gold-platinum district, Albany and Carbon Counties, Wyoming: Geological Survey of Wyoming Preliminary Report 8, 12 p.
McCallum, M.E., and Waldman, M.A., 1991, The diamond resources of the Colorado-Wyoming State Line district: kimberlite indicator mineral chemistry as a guide to economic potential, in B.R. Frost and Sheila Roberts, editors, Mineral resources of Wyoming, Wyoming Geological Association 42nd Field Conference Guidebook, p. 77-90.
McCandless, T.E., Nash, W.P., and Hausel, W.D., 1995, Mantle indicator minerals in ant mounds and conglomerates of the conglomerates of the southern Green River Basin, Wyoming: WGA Resources of Southwestern Wyoming Guidebook, p. 153-163
Newhouse, W.H., and Hagner, A.F., 1949, Cordierite deposits of the Laramie Range, Albany County, Wyoming: Wyoming Geological Survey, University of Wyoming, Bulletin 41, 18 p.
Nowell, W.B., 1971, The petrology and alteration of the Kirwin mineralized area, Park County, Wyoming: M.S. thesis, University of Montana, Missoula, 72 p.
Ogden, P.R.,1979, The geology, major element chemistry, and petrogenesis of the Leucite Hills volcanic rocks, Wyoming: PhD dissertation, University of Wyoming, Laramie, 137 p.
Osterwald, F.W., Osterwald, D.B., Long, J.S., Jr., and Wilson, W.H., 1960, Mineral resources of Wyoming: Geological Survey of Wyoming Bulletin 50, 287 p.
Pay Dirt, 1985, Do you want a mine or a beautiful summer retreat? See AMAX: Rocky Mountain Pay Dirt, October, p. 32A.
Pfaff ,B.C.,1978, Atlantic City nuggets: Baroil, Wyoming, 155 p.
Reinking, R.L., and Hagner, A.F., 1969, Geochemistry and origin of the Titaniferous Magnetite deposit, Iron Mountain, Wyoming: Wyoming Geological Survey Mineral Report 69-1, 23 p.
Schrader, F.C., 1913, Gold placers on Wind and Bighorn Rivers, Wyoming: U. S. Geological Survey Bulletin 580, p. 127-142.
Sherer, R.L.,1969, Nephrite deposits of the Granite, the Seminoe, and the Laramie Mountains, Wyoming: Ph.D. dissertation, University of Wyoming, Laramie, 194 p.
Silver Lake Resources, Inc.,1985, Annual Report for 1985: Geological Survey of Wyoming Mineral files, 27 p.
Smaglik, S.M.,1987, Petrogenesis and tectonic implication for Archean mafic and ultramafic magmas in the Elmer's Rock greenstone belt, Laramie Range, Wyoming: M.S. thesis, Colorado School of Mines, Golden, 126 p.
Smith, C.B., McCallum, M.E., Coopersmith, H.G., and Eggler, D.H.,1979, Petrochemistry and structure of kimberlites in the Front Range and Laramie Range, Colorado-Wyoming, in F.R.Boyd and H.O.A.Meyer, editiors, Kimberlites, diatremes, and diamonds: their geology, petrology, and geochemistry, American Geophysical Union, Washington, D.C., p. 179-189.
Snyder, G.L., Hausel, W.D., Klein, T.L., Houston, R.S., and Graff, P.J.,1989, Precambrian rocks and mineralization, southern Wyoming Province: 28th International Geological Congress Field Trip Guidebook T332: American Geophysical Union, Washington D.C., 48 p.
Spencer, A.C.,1916, The Atlantic gold district and the north Laramie Mountains: U.S. Geological Survey Bulletin 626, 85 p.
Spry, P.G., and McGowan, K.I.,1989, Origin of Archean lode gold mineralization at Atlantic City-South Pass, Wyoming: fluid inclusion and stable isotope study: 28th International Geological Congress Abstracts, American Geophysical Union, Washington D.C., p. 3-163.
Staatz, M.H.,1983, Geology and descriptions of thorium and rare earth deposits in the southern Bear Lodge Mountains, northeastern Wyoming: U.S. Geological Survey Professional Paper 1049-D, 52 p.
Sutherland, W.M., 1990, Gemstones, lapidary materials, and geologic collectables in Wyoming: Geological Survey of Wyoming Open File Report 90-9, 53 p.
U.S. Bureau of Mines, 1942, Rambler mine, Albany County, Wyoming: War Minerals Report 17, 7 p.
Welch, C.M., 1974, A preliminary report on the geology of the Mineral Hill area, Crook County, Wyoming: M.S. thesis, South Dakota School of Mines and Technology, Rapid City, 83 p.
Wilson, W.H., 1960, Petrology of the Wood River area, southern Absaroka Mountains, Park County, Wyoming: Ph.D. dissertation, University of Utah, Salt Lake City, 121 p.
Wilson, W.H., 1964, The Kirwin mineralized area, Park County, Wyoming: Geological Survey of Wyoming Preliminary Report 2, 20 p.
Woodfill, R.D.,1987, Hartville uplift, southeastern Wyoming: Geological Survey of Wyoming mineral files (unpublished), 20 p.
