The GOLD HUNTER

The Search for Gold, Silver, Platinum Groups & Gemstones

Some of My Favorite Wyoming Targets

Important work in Wyoming's Black Hills was completed by Welch and Gersic and others. Following their work, the author investigated some properties in htis region. It is obvious that Mineral Hill has two horizontal veins and breccias that are highly anomalous in gold. For example, the author was able to retrieve a channel sample that assayed >4 opt Au and >10 opt Ag. This should be considered high priority. Other targets should include buried porphyry copper and rare earth deposits, gold-breccias, as well as replacement Au-Ag-Cu-Pb-Zn deposits. Some of the mineralization has similarities to the Rattlesnake Hills.

The Black Hills in Wyoming encloses the Bear Lodge, Mineral Hill, and Black Butte districts. These occur along a dome-shaped uplift that extends into South Dakota and is cored by a 2.6 billion year old Precambrian complex surrounded by Paleozoic and Mesozoic limestone, shale, and sandstone.  Tertiary alkalic and peralkalic igneous rocks intrude older rocks at a number of locations.  The intrusives range in age from 30 Ma to 55 million years, and include the Bear Lodge Mountains complex, Black Buttes, Devils Tower-Missouri Buttes, Inyan Kara Mountain, Mineral  Hill, and Sundance Mountain (Lisenbee, 1985).  Of these, mineralization has been reported in the Bear Lodge Mountains, Black Buttes, and the Mineral Hill district.

The Bear Lodge Mountains include disseminated gold and rare earth (REE) mineralization in addition to copper. Copper appears to be relatively widespread, but in uneconomic concentrations at the surface, but economic porphyry deposits are likely at depth. Chalcopyrite is reported with fluorite in trachytes and leucosyenites in accessory amounts.  Pseudoleucite alkali trachyte porphyry in the Bear Lodge Mountains carries accessory chalcopyrite, sphalerite and galena. In the Black Butte area, replacement deposits are dominated by argentiferous silver and hemimorphite with subordinate fluorite and wulfenite. Copper is uncommon. In the Mineral Hill district, disseminated gold and gold- and silver-rich veins dominate with some scattered REE, copper, lead, zinc, and tin.

The Bear Lodge Mountains form a large multiple intrusive complex of alkalic igneous rock ranging in age from 38 to 50 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 US. Disseminated gold is associated with feldspathic breccia in the complex (Jenner, 1984). One mineralized zone discovered in an elongate intrusive breccia (2,000 by 120 ft) was drilled yielding gold values of 0.343 to 1.72 ppm (Anonymous, 1988). Current 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, aTertiary 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 (parts per million) Au and 115 ppm Ag, and jasperoids with 5 ppm Au and 7 ppm Ag. The possibility for similar mineralization at Black Buttes, 6 miles to the southwest, is indicated by the presence of epithermal replacement galena, wulfenite, fluorite, and hemimorphite in altered Pahasapa Limestone along a contact with Tertiary alkalic igneous rock (Hausel, 1989).

Mineral Hill district

The Mineral Hill district lies adjacent to the Tinton district in South Dakota. Tinton was known for tin (cassiterite): Mineral Hill was principally known for placer gold. In addition to placer gold, other valuable heavy minerals were found in the surrounding drainages. The district also contains lode and disseminated gold, some copper, and minor amethyst.

Mineral Hill is dominated by a Tertiary alkalic complex that intrudes Precambrian biotite-quartz schist, minor amphibolite and pegmatite, and Paleozoic sedimentary rock. The Paleozoic rocks are domed and dip gently away from the center of the alkalic complex.

The Deadwood Formation (Cambrian), the lowermost Paleozoic unit exposed in the Mineral Hill area, forms a semi-circular outcrop around the Mineral Hill ring-dike complex. The Deadwood crops out as conglomerate and quartzite overlain by laminated carbonate-rich siltstone, sandstone, and flat-pebble conglomerate. Isolated pods and veins of jasper have been identified in these rocks (Welch, 1974).

The Mineral Hill alkalic complex has an outer ring dike of alkali trachyte porphyry, a pyroxenite inner ring dike, and a core of feldspathic breccia intruded by diorite (Figure 14). Alkalic lamprophyre and pseudoleucite porphyry dikes are scattered over a wide area (Welch, 1974).

On the west side of Mineral Hill, the alkali trachyte porphyry forms extensive sills at the base of the Deadwood Formation, intrudes various horizons of the Deadwood Formation, and occurs locally in younger Paleozoic rocks. East of Mineral Hill, the trachyte porphyry forms vertical sills conformable to the schistosity of the Precambrian schist. The central portion of the complex is crudely circular in outcrop and consists of pyroxenite and feldspathic breccia.

The complex exhibits varying degrees of alteration that Welch (1974) attributed to deuteric processes. Although some bleached rocks are completely replaced by K-spar and clay, Welch insisted that fenites do not occur in the complex.

The igneous complex was emplaced during the Laramide orogeny. A crustal fracture is believed to have tapped alkalic peridotitic magma from the mantle, which produced pyroxenitic magma (Welch, 1974). Welch also postulated a second magma generated by partial melting of the crust by the pyroxenitic magma, was responsible for the alkalic trachyte porphyry.

Mineralization includes disseminated and vein deposits.  Anomalous copper, gold, silver, lead, manganese, and zinc occur throughout the ring complex. Precambrian pegmatites contain columbite-tantalite as well as tin. Reported production for the district included 9,000 ounces of placer gold prior to 1893 (Knight, 1893). 

Artic mine; N/2 section 32, T51N, R60W. Samples collected from the Artic 1 and 2 mines by the author in 1990, contained common crusts of lavender to purple drusy quartz. One sample of amethyst was found in the back of the Artic 2 adit. A sample of silicified limonite-stained intrusive breccia collected by Gersic and others (1990) from the mine dump yielded 0.023 ppm Au and 1.6 ppm Ag. Other samples collected by the author were also poorly mineralized (Hausel, 1990c).

Assay results of samples collected from the Artic mine dump (Hausel, 1990c).                                                                                                                    

Sample Description                                                                        Au (ppm)      Ag (ppm)

        Chalcedony-bearing trachyte (#2 adit).                                       0.019              -

        Chalcedony-rich trachyte (#1 adit).                                             0.029              -

        Chalcedony-rich trachyte (#1 adit).                                             0.060            2.4

Birdsnest mine; SE SW section 29, T51N, R60W.  Four samples collected from the Birdsnest mine yielded anomalous metal values.

Assay results of samples collected from the Birdsnest mine (Hausel, 1988c; 1990c). 

                                                                               

Sample Description            Cu (%)     Au(ppm)    Ag (ppm)     Mn(%)       Pb(ppm)     Zn(ppm)

Pyroxenite w/pyrite.            -           0.168            -                 -                -                -

afic breccia w/pyrite             -           0.002           -                  -                -                -

quartz w/pyrite.                0.29         15.0          120.0             -                -                 -

Altered trachyte.               0.04          nd             nd              0.42            471           441   

Bull Hill; E/2 SE section 30, T51N, R60W. A sample of brown jasperoid in pulaskite assayed 470 ppm Cu, 4,300 ppm Pb, 5 ppm Au, and 7 ppm Ag (Welch, 1974). 

Interocean mine; S/2 section 29, T51N, R60W. The mine consists of a collapsed shaft sunk in diorite and a 35-foot adit driven below the shaft in schist (Gersic and others, 1990).  Mineralized diorite assayed 0.2% Cu, 29 ppm Pb, 3 ppm Au, and 1 ppm Ag. Preliminary tests indicated the presence of an ore body with an average gold content between 0.08 and 0.14 opt Au (Welch, 1974). 

Two samples of silicified trachyte breccia were collected from the mine dump by the author. These yielded no detectable (nd)gold and 0.43 ppm Au; no detectable silver and 2.5 ppm Ag; 622 ppm Cu and 0.12% Cu; 0.19% Mn and 0.83% Mn; no detectable lead and 88 ppm Pb; and 100 ppm and 146 ppm Zn (Hausel, 1988c). A 1-foot chip sample taken across the intersection of two veinlets at the portal of the adit by the U.S. Bureau of Mines* yielded 0.13 opt Au, 0.09 opt Ag, and 0.29% Cu. Another sample from an 8 inch wide pegmatite yielded 0.028 ppm Au and 0.7 ppm Ag (Gersic and others, 1990).

Peterson mine located on the line between sections 29 and 32, T51N, R60W on the west side of Mineral Hill. The Peterson mine was driven 1,450 feet. A grab sample of silicified and limonite-stained intrusive breccia from the dump yielded 1,367 ppm Pb, 1,041 ppm Zn, 396 ppm As, 65 ppm Sb, 0.04 ppm Au, and 2.5 ppm Ag (Gersic and others, 1990). 

Treadwell mine; S/2 section 29, T51N, R60W. Consists of a small open cut with high walls and two parallel adits driven on one-foot-wide horizontal veins. The pit was developed to recover ore from two horizontal quartz veins in altered feldspathic syenite and trachyte and possibly from the altered host rock. Welch (1974) collected a sample of silicified intrusive breccia from the pit that assayed  0.17 opt Au, 3.36 opt Ag, 1.1% Cu, and 0.57% Pb. A few samples collected by Hausel (1990d) were mineralized.

Assay results of samples collected from the Treadwell mine (Hausel, 1990d).                                                                                                        Cu               Pb               Au               Ag

Sample Description                                                    Cu(%)       Pb(%)      Au(ppm)      Ag(ppm)

Feldspathic breccia from mine dump.                   -              -           <0.005          <5.0

Breccia.                                                            -              -           <0.005          <5.0

Graphitic sulfide-bearing nodule.                         -              -            <0.05           <1.0

Limonitic quartz vein from high wall.                   0.29         2.32         130.0          330.0

Limonite-stained syenite.                                    -              -             0.06           <1.0

Silicified trachyte.                                               -              -             1.39             9.0

Silicified porphyry.                                               -              -           <0.05           <1.0

Quartz vein from high wall.                                   -              -             0.36           <5.0

Vertical fracture vein from high wall.                       -              -           0.056           <5.0

Limonitic quartz vein from high wall.                     0.19        1.47          21.0            65.0

NE section 29, T51N, R60W. A sample collected in this area in 1960 assayed 3% Pb and 17 opt Ag. Welch (1974 )resampled the area but was unable to repeat the results.

N/2 NW section 32, T51N, R60W. A quartz vein in altered igneous rock assayed 65 ppm Cu, 3,000 ppm Pb, 0.9 ppm Au, and 3 ppm Ag (Welch, 1974).

N/2 section 32, T51N, R60W.  Samples collected from trenches dug in intrusive breccia yielded 0.027 and 0.005 ppm Au, and 0.7 and 1.7 ppm Ag (Gersic and others, 1990).

E/2 section 32, T51N, R60W. A sample of feldspathic syenite contained 0.016 ppm Au and 0.4 ppm Ag (Gersic and others, 1990).

Section 32, T51N, R60W. Humble Oil and Refining Company drilled Mineral Hill and intersected large intervals of disseminated pyrite and chalcopyrite, locally. One of the holes spudded in pyroxenite and was drilled to a depth of 740 feet and averaged 380 ppm Cu. Some 10-foot intervals in this hole averaged 900 ppm Cu. A few zones in the pyroxenite contained as much as 25% titanomagnetite (Gersic and others, 1990).

W/2 W/2 section 22,  T51N, R60W. A hole drilled in pyroxenite along the southwestern margin of Mineral Hill by Exxon in 1970, yielded anomalous copper. According to Welch (1974) trace chalcopyrite was observed throughout much of the 3,000 feet of drill core.

NE section 29, T51N, R60W. A sample of bleached breccia collected along the edge of Spottedtail Gulch on the north side of Mineral Hill yielded 220 ppm Cu, 61 ppm Pb, 1.0 ppm Ag, and no gold. A sample of brown limonite collected nearby yielded 600 ppm Cu, 23 ppm Pb, 1.0 ppm Ag, and no gold (Welch, 1974).

Center section 29, T51N, R60W. A sample of a gray igneous dike with abundant pyrite collected along Spottedtail Gulch by Welch (1974) yielded 280 ppm Cu, 38 ppm Pb, 2 ppm Ag, and no gold.

SW section 28, T51N, R60W. A sample from the dump of a caved adit consisted of silicified, pyritized, and brecciated biotite schist.  The sample assayed 0.335 ppm Au, and 0.7 ppm Ag  (Gersic and others, 1990).

Bald Mountain-Kirwin

The Kirwin mining district is located near the headwaters of the Wood River (T45-46N, R104W), 30 miles west-southwest of Meeteetse in the southern Absaroka Mountains. Meeteetse is 28 miles south of Cody along Highway 120. At Meeteetse, take Highway 290 (Pitchfork Road) 7 miles to the west-southwest to its intersection with the Wood River Road. From here, the Kirwin trailhead is 20 miles to the southwest. From the trailhead, it is 6 miles of hiking to Bald Mountain and the Kirwin district lies in bear country. Search Google Earth or Virtual Earth for 43o52’10.30”N; 109o17’11.30”W: this will place you right at Bald Mountain. As you examine aerial photos, you will see numerous roads that mark old drill sites. This is the Bald Mountain porphyry and the entire mountain is mineralized and would have been mined as open pit with associated underground operations providing dozens of jobs to people from Cody. The district is located at 9,000 feet elevation thus it lies under snow much of the year. The district at one time contained patented property held by AMAX who apparently sold the property to the Mellon Foundation. The Mellon Foundation promptly sold to the US Forest Service which withdrew the property from exploration and mining with little public input.

 

The district coincides with three mineralized porphyries, numerous veins and a significant resource of unexplored gravel downstream from the porphyries and veins. Early development of the district began near the turn of the 19th century and available records indicate that 12,000 to 15,000 feet of drifts were dug from shafts and adits to explore veins. Production, however, was limited to only one carload of ore with a net value of $65 per ton after smelter and transportation charges were deducted. The ore minerals include pyrite, chalcopyrite, sphalerite, galena (lead-sulfide), tetrahedrite (copper-antimony-sulfide), molybdenite (molybdenum sulfide), stephanite (silver-antimony-sulfide), limonite, malachite (copper-carbonate), azurite (copper carbonate), cuprite (copper oxide), and native gold. Gangue minerals include specular hematite, siderite, barite, calcite, quartz (amethystine) and dolomite (Hewett, 1912).

 

The three intrusive complexes (Bald Mountain, Brown Mountain and Meadow Creek) penetrate volcanics of the Wiggins Formation (Eocene). The Brown Mountain and Meadow Creek porphyries are relatively unexplored and potentially could have provided additional resources to the Bald Mountain porphyry if it would have been developed. The Wiggins Formation is one of a group of formations of the Thorofare Creek Group (Smedes and Prostka, 1972). The Wiggins Formation forms a series of deuterically propylitically altered hornblende-biotite and pyroxene andesite porphyry flows, tuffs, breccias and volcaniclastics. The vent-facies layered volcanics have been domed, hydrothermally altered, and radially fractured. Andesite porphyry dikes occupy radial fractures and N-NW-trending fractures. With few exceptions, the mineralized veins occupy N-NW-trending fractures. These veins are predominantly lead-silver-zinc veins. In the altered zone on the northern flank of Bald Mountain, the veins are copper-molybdenum dominant.             

 

Many of the veins have been partially explored along strike, even though some appear to be as long as 2,500 feet with zones of strong mineralization over mineable widths. The silver and gold assays from this region are notable and in many cases the precious metal assays are high enough to mine commercially. The Oregon vein, for example, yielded ore-grade values of 17.8 opt Ag and 0.08 opt Au across 3-foot widths. The Little Johnnie vein yielded 64.7 opt Ag and 0.12 opt Au across widths of 1.5 feet. According to Rostad (1982), the best values on these veins were obtained at or next to the mine face of the adits (where work had stopped).

 

So how valuable are these veins. With today's economy and terrible unemployment rate, if our government would open this area to mining, some people could make a very nice living. For example, the Mendota vein yielded ore grade material. A select sample across 0.5-foot width of the vein in the Galena Ridge tunnel averaged 101.35 opt Ag and 0.283 opt Au. At today’s precious metal prices (April 10th), this vein contains $417/ton in gold and $4155/ton in silver for a total of $4572/ton! Such a deposit would bring incredible wealth to a small mining operation or family mining operation. This high-grade zone is enclosed by an untested lower grade segment that brings the vein width to 4.3 feet. The average of 31 samples taken over a strike length of 98 feet on the Bryan vein on Spar Mountain averaged 0.13 opt Au, 29.5 opt Ag and 0.73% Cu (Rostad, 1982). Based on these samples, some veins are economic and the associated disseminated mineralization surrounding the veins suggests the district has several commercial mineral deposits and should never have been taken from the public.

 

Assay results from samples from various mines in the Kirwin district (from Rostad, 1983 and Wilson, 1964).

Claim                            Au (opt)       Ag(opt)        Cu (%)         Pb(%)          Zn(%)         Mo(%)          Sample Type

Bryan                                0.04             4.2                -                   -                   -                   -                Dump-grab

Bryan                                0.25           30.5               2.33             tr                   -                  tr                Dump-grab

Bryan #2                        0.13          29.6               0.73            -       - -    Ave. 98 ft of                                                                                                                                                vein in portal

Wolf shaft                         tr                  tr                   -                  tr                   -                  0.55           Dump-grab

Oregon                              0.03           10.8                -                  0.1                -                   -                Vein-channel

Oregon                              0.11           28.9               0.2               2.5                -                   -                Dump-grab

Oregon                              0.05             9.32              -                   -                   -                   -                Ave 120 ft of vein

Oregon                              0.07           15.85              -                   -                   -                   -                Dump-ore

Smuggler                           0.06             8.1               0.8                -                   -                   -                Opencut-grab

Smuggler                           0.07             4.8               0.2                -                   -                   -                Dump-grab

Pickwick                           0.09             1.5                -                   -                   -                   -                Dump-grab

Pickwick                           0.04             4.3                -                   -                   -                   -                Vein-channel

Pickwick                           0.03             2.2                -                   -                   -                   -                Vein-channel

Pickwick                           0.15           28.0               tr                  tr                   -                   -                Large sample

Tumlum                             0.02           17.6                -                  3.2                -                   -                Dump-grab

Tumlum                             0.07           41.1                -                31.9                -                   -                Dump-grab

Illonies                              0.02             0.2                -                   -                   -                  0.51           Dump-grab

Illonies                             tr                  tr                  0.5               tr                   -                  0.14           Dump-grab

Anaconda shaft                 0.03             1.4                -                20.6                -                   -                Dump-grab

Anaconda shaft                 0.04           11.9                -                61.8                -                   -                Shaft-grab

Anaconda shaft                 0.02             7.3               tr                39.9                -                   -                Dump-grab

Anaconda shaft                 0.03             6.71              -                23.4                -                   -                1 ft down

Anaconda shaft                 0.03             3.87              -                  9.7                -                   -                9 ft down

Anaconda shaft                 0.01             1.37              -                   -                   -                   -                19 ft down

Black Prince                      0.06             6.0               0.2               3.1                -                   -                Outcrop

Black Prince                      0.10             1.22              -                   -                   -                   -                Ave 44 ft of vein

Little Johnnie                     0.01             1.5                -                  1.1                -                   -                Vein-grab

Little Johnnie                     0.19         111.8               0.03              -                  1.2                -                Dump-bulk

Little Johnnie                     0.07           29.5                -                   -                   -                   -                Ave 82 ft of vein

Little Johnnie                     0.12           64.7                -                   -                   -                   -                Mine face

Little Johnnie                  nd              156.0                -                   -                   -                   -                Specimen from                                                                                                                                                       dump

Little Johnnie                     0.09           43.1                -                   -                   -                   -                Shipment

Mendota                            0.04           14.7                -                  0.55              -                   -                Dump-grab

Mendota                            0.08           21.2                -                   -                   -                   -                Second cut.  Mendota              0.04         2.38         -                                           -                   -                   - Upper tunnel face

Mendota                            0.28         101.0                -                   -                   -                   -                High grade

Manilla                              0.06             5.86              -                   -                   -                   -                Upper tunnel face   

Iowa                                  0.06             3.84              -                   -                   -                   -                Lower cut

Iowa                                  0.02             2.66              -                   -                   -                   -                Main adit at face

Iowa                                  0.12             8.76              -                   -                   -                   -                Second cut

Krachy                               0.10             7.10              -                   -                   -                   -                Ore dump

Krachy                               0.10             4.14              -                   -                   -                   -                Cut

Krachy                               0.10             0.64              -                   -                   -                   -                Outcrop on summit                                                                                                                                     north of shaft

Krachy                               0.15             4.55              -                   -                   -                   -                Outcrop on summit                                                                                                                                     north of shaft

Krachy                               0.15           17.68              -                   -                   -                   -                Outcrop 100 ft                                                                                                                                             north of shaft

 

The mineralized area continues southeast of Kirwin into the Stratified Primitive area. Samples collected in the Stratified Primitive area yielded anomalous copper, molybdenum, zinc, lead and silver (Ketner and others, 1966). This area should never have been incorporated into a primitive area without thorough investigation nor should the district have been withdrawn from mining and exploration as the Kirwin district is a multi-billion dollar resource.

 

Alluvial gravel is abundant in the Wood River downstream from the ghost town of Kirwin. The gravels are reported to range from 60 to 150 feet deep and estimated that the Wood River has a potential for >100 million cubic yards of gravel, essentially all of it unexplored for gold! Little evidence exists that the gravel has ever been explored, even though geologic evidence suggests it will be mineralized (Rostad, 1982).

 

Bald Mountain Porphyry

The Bald Mountain mineralized porphyry is located at Bald Mountain near the southern edge of the Kirwin district. The complex is expressed by an oval-shaped, intense zone of hydrothermal alteration. Mineralization is associated with a volcanic vent complex with intrusive rhyolitic tuff breccia (Wilson, 1964; Nowell, 1971) known as the Kirwin Formation. Brecciation appears to be more intense along the edge of the vent. The geology, mineralization and wall rock alteration are characteristic of porphyry copper-silver deposits found elsewhere in the world such as Arizona, Utah and New Mexico (Hausel, 1982).

 

Hydrothermal alteration increases in intensity towards the center of Bald Mountain. Outside the altered zone, Wiggins Formation andesites are deuterically altered and exhibit propylitic assemblages (calcite, chlorite and clays). Within 1,500 feet of the mineralized center, andesites are hydrothermally altered to quartz, calcite, epidote and montmorillonite with disseminated chalcopyrite and chalcopyrite-bearing quartz-calcite veinlets. Closer to the volcanic center, the rocks take on characteristics of argillic and phyllic alteration and have secondary sericite, mixed-layer illite-montmorillonite, quartz and biotite with lesser kaolinite and chlorite. Epidote and calcite are nonexistent in this zone. A central potassic altered zone is not well-defined, but indicated by the presence of secondary orthoclase with quartz and veinlet sulfides (Nowell, 1971). 

 

Drill-hole data for Bald Mountain show stockwork mineralization with pyrite, chalcopyrite and molybdenum. Weathering of the stockwork produced a leached cap over a blanket-like supergene copper deposit. Chalcocite is the principal sulfide with some covellite and digenite. Veins in the altered area are pyrite-chalcopyrite-molybdenite-quartz veins (Wilson, 1960). The mineralized porphyry is about 3,900 feet across (Rostad, 1983).

 

The Bald Mountain porphyry was explored by AMAX between the 1960s through the early 1980s.  The company began drilling Kirwin in 1963 and intersected significant secondary-enriched porphyry-copper mineralization (Rostad, 1983). Drilling over the next several years included 150 holes totaling 86,861 feet. The project outlined geologic reserves totaling 196 million tons of ore averaging 0.505% Cu and 0.022% MoS2 with significant byproduct silver and gold. The resource was calculated using a 0.3% Cu cutoff grade. Open pitable reserves were calculated at 160,800,000 short tons with a favorable stripping ratio of 0.57:1 of waste to ore (Rostad, 1983). Feasibility studies indicated that the deposit was also amenable to in situ leaching. A 1991 study indicated that copper could be recovered at a cost of only $0.309/pound by in situ leaching (Ora Rostad, personal communication, 1992). Copper prices today are more than 10 times that value. Also keep in mind that this deposit also has considerable associated precious metals.

 

Copper reserves reported for the Bald Mountain porphyry at Kirwin (Rostad, 1983).

Mineable Reserves, tons (Open Pit)                                                         Cutoff Grade______________                                     

                                                                                     0.3% Cu                           0.4%Cu                          0.5% Cu

Geologic                                                                     196 million                     125.3 million                    64.2 million

Pit                                                                             160.8 million                             -                                       -

%Cu (total)                                                                     0.505                                0.56                                  0.7

%Cu (sulfide)                                                                 0.467                                   -                                       -

%MoS2                                                                          0.022                                   -                                       -

Waste:Ore ratio                                                              0.57:1                                  -                                       -

Pre-production stripping                                             8.5 million                               -                                       -

 

Unexplored targets in the immediate area of Bald Mountain could greatly expand the identified reserves. For example, the Kirwin Formation is a breccia pipe typically found with porphyry copper deposits. Many such pipes are highly mineralized. AMAX's 300-foot drill-hole spacing likely missed other breccia pipes. Spar Mountain, south of Bald Mountain could also represent a separate mineralized center with possible secondary-enriched copper. This is supported by widespread limonitic alteration on the talus-covered Spar Mountain and by samples of native copper that have been recovered downstream from the divide between Smuggler Basin and Spar Creek. Potential also exists for skarn and replacement deposits where veins project down-dip into the underlying sedimentary rocks. These conditions are similar to the lead-copper-zinc-silver-gold replacement deposits at Camp Bird, Colorado, and the lead-silver-zinc ores of the Irma-Republic mine in the New World district, Montana-Wyoming. Such deposits could be mined relatively cheaply by room-and-pillar methods (Rostad, 1982).  In other words, the Kirwin reserves would likely be greatly increased with additional exploration and mining.

 

*Politicians & bureaucrats seem to be only concerned with controlling others and lining their pockets with money. The US Bureau of Mines was one of the most productive government agencies in the world along with NASA and the USGS. During the Clinton Administration, this agency was eliminated as it did not fit in the green agenda of Clinton and Gore.