Mountain View: Fish Creek nos. 1; 2 and 3; Skookum; Gray Copper; Ruby Silver Mine, Hyder Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi

Regional Level Types
Mountain View: Fish Creek nos. 1; 2 and 3; Skookum; Gray Copper; Ruby Silver Mine	Mine
Hyder Mining District	Mining District
Prince of Wales-Hyder Census Area	Census Area
Alaska	State
USA	Country

Location: The Mountain View group of claims lies mainly at an elevation of 500-600 feet between Skookum and Fish creeks just above their junction, but in part below it. The site is in section 11, T. 68 S., R. 99 E., of the Copper River Meridian. It mainly represents the Fish Creek nos. 1, 2, and 3 claims, which cover the main workings, called the 'Skookum tunnel' (Byers and Sainsbury, 1956, pl. 8). These claims also cover the 'Gray Copper' and 'Ruby Silver' veins, located at about 900-1000 feet elevation near the north end of the claim group (Maas and others, 1995, p. 262). The site corresponds to loc. 1 on plate 2 in Buddington (1929 [B 807]); to plate 11 in Byers and Sainsbury (1956); and to loc. 6 in Elliott and others (1978). The location is accurate within 0.2 mile.
Geology: The country rocks in the area of this site include: pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or Triassic Hazelton Group; recrystallized granodiorite of the Triassic Texas Creek Granodiorite, which intrudes the Hazelton rocks; quartz monzonite and granodiorite of the Hyder Quartz Monzonite batholith, which intrudes the Hazelton and Texas Creek rocks; and Tertiary lamprophyre dikes, which intrude all of the foregoing rock units (Buddington, 1929; Smith, 1973, l977; Berg and others, 1988). The deposits consist of quartz fissure veins in (Texas Creek) granodiorite and Hazelton metasedimentary rocks (Buddington, 1929, p. 63-67; West and Benson, 1955, p. 31-45; Byers and Sainsbury, 1956, p. 137-138; Cobb and Elliott, 1980, p. 78). The Texas Creek-Hazelton contact is a north-trending, high-angle fault that runs through the middle of the property; the Hazelton lays east of the fault. The veins locally are cut by dikes of aplite and granodiorite porphyry or pegmatite that probably are apophyses of the Hyder Quartz Monzonite batholith, and by lamprophyre dikes. The veins range in thickness from an inch or so to as much as 8 feet, and have been traced in surface or underground exposures for as much as 475 feet. The veins contain sulfide minerals, occasionally in massive shoots up to several inches thick, that mainly include pyrite, pyrrhotite, chalcopyrite, galena, sphalerite, and minor tetrahedrite and freibergite. Free gold and native silver have been reported, as have secondary oxides of the copper, lead, silver, and iron sulfides. A secondary, radioactive mineral, tentatively identified as uranium sulfate, occurs as a thin, yellowish coating on some of the sulfide and oxide minerals and on fracture surfaces; the primary radioactive mineral, which appears to be associated with rutile, has not been identified (West and Benson, 1955, p. 41). The Fish Creek no. 2, or Gray Copper, vein contains scheelite and barite in addition to the sulfides. Molybdenite flakes occur in some of the aplite and pegmatite dikes. On the basis of lead-isotope studies, Maas and others (1995, p. 254) established that the age of the Gray Copper vein is Eocene, and suggest that the Ruby Silver vein also is Eocene. The veins thus are roughly contemporaneous with the emplacement of the Hyder Quartz Monzonite batholith. More than 3600 feet of underground workings were driven at the Mountain View mine between 1925 and 1944, but the only ore shipments were for mill tests.
Workings: From 1925 to 1929, a total of 3600 feet of tunnels were driven at the Mountain View mine. Of these workings, 3500 feet are in the Skookum tunnel at an altitude of 540 feet. In 1944, the northwest drift of the Skookum tunnel, on the Gray Copper vein, was extended for 180 feet. The weighted average tungstic oxide (WO3) content of 43 channel samples in these workings was 1.23% across an average vein width of 1.4 feet for a strike length of 130 feet (Byers and Sainsbury, 1956, p. 137). This ore also averaged 0.1 oz. Au/ton and 6.4 oz. Ag/ton. Weighted averages of channel samples of other parts of this vein varied from 0.15-3.93% WO3. Samples of molybdenite-bearing granodiorite contained 28-1446 ppm Mo (Maas and others, 1995, p. 262, no. 426). The most highly radioactive unconcentrated vein sample contained 0.049 percent equivalent uranium, and the most intensely radioactive concentrate of vein material contained 0.398 percent equivalent uranium (West and Benson, 1955, p. 25).
Age: On the basis of lead-isotope studies, Maas and others (1995, p. 254) established that the age of the Gray Copper vein is Eocene, and suggest that the Ruby Silver vein also is Eocene. The veins thus are roughly contemporaneous with the emplacement of the Hyder Quartz Monzonite batholith.
Alteration: Oxidation and supergene enrichment of some copper, silver, lead, and uranium minerals.
Production: More than 3600 feet of underground workings were driven at the Mountain View mine between 1925 and 1944, but the only ore shipments were for mill tests.

Commodities (Major) - Ag, Au, Cu, Mo, Pb, W, Zn; (Minor) - Barite, U
Development Status: No
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c)

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Link to USGS - Alaska:	KC006

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