Cove Mine, McCoy Mining District, Lander County, Nevada, USAi

Regional Level Types
Cove Mine	Mine
McCoy Mining District	Mining District
Lander County	County
Nevada	State
USA	Country

Structure: Faults

Alteration: Argillization, Silification, Manganese Alteration. See Geology Comments.

Commodity: In the upper ore zone, Au and Ag mineralization are associated with argillization and with penetrative Mn replacement. In the lower ore zone, Au and Ag mineralization are associated with disseminated sulfides, sulfide veinlets, and high pb and zn contents.

Deposit: The cove deposit consists of two main ore zones that are stacked. The upper zone is hosted by lower augusta mountain formation, the lower zone by the panther canyon formation. Dimensions are for the upper zone, followed by the lower zone. This record has been merged with m242946, which has been deleted.

Deposit type: Distal disseminated Ag-Au

Development: Expl.com: in january, 1986, tenneco minerals corp. Began a mccoy district exploration program, the purpose of which was to evaluate the triassic rocks which host the mccoy gold skarn deposit. Work consised of stream sediment sampling, soil sampling, rock sampling, and geologic mapping. By early 1986, 500 stream sediment samples had been collected from the 8 square miles which surround the mccoy mine. Au values for all samples ranged from <1 ppb to 34 ppm; for samples in the vicinity of the cove deposit, Au values ranged up to 72 ppb with anomalous ag, hg, as, sb, tl. Follow-up outcrop sampling in the cove area identified a zone of over 1000 ft. Of strike length with Au values ranging from 0.1 - 1.9 ppm. In september and october, 1986, soil sampling was conducted in the cove area. 147 soil samples were collected of the b and c soil horizons on a 100 ft. By 200 ft. Grid spacing. A geochemical anomaly approx. 2800 ft. Long and 100-1000 ft. Wide with Au values up to 2600 ppb and As values up to 1000 ppm was identified. The eastern portion of this Au-as anomaly was also anomalous in Ag (up to 210 ppm, or 6 opt!). In late 1986, dozer trenching indicated ore -grade mineralization over the strike length of the soil geochemical anomaly. In january , 1987, a 25 hole reverse circulation drilling program of 5000 ft. Was started. The first hole intersected 110 ft./0.024 opt au, 0.92 opt ag. Drill hole cove 19 intersected 170 ft./0.167 opt Au starting at surface. Drill hole cove 35 intersected 85 ft./0.5 opt au, 1.4 opt Ag starting at surface. Drill hole cove 36 was the first to encounter panther canyon formation, intersecting 45 ft./0.163 opt au, 50 opt ag. By march, 1987, 42 holes had been drilled to a maximum depth of 475 ft. Discovery was announced march 31, 1987. Initial development drilling began in march, 1987 with 2 drills operating 1 shift/day. By may, these 2 drills were operating 2 shifts/day. By december, 5 drills were operating 24 hrs./day. By the end of 1988, more than 400,000 ft. Of reverse circulation drilling in 475 holes and 38,000 ft. Of diamond drilling in 25 holes had been completed. Haul road construction began december, 1987, and limited mining operations began january, 1988, one year after discovery. Full scall mining began march, 1988. Initial mining rate was 75,000 tpd of ore and waste. Mill construction began in 1988, scheduled for mid-1989 completion. In early 1989, additional development angle diamond drill holes were being drilled underneath the cove open pit. The final mine plan will probably include underground mining. Claim block consists of 75 square miles. ; total$: 220 ; mill.cap: 10,000 tpd (est.) ; econ.com: in 1989, a factor of 55:1 was used to convert Ag to Au equivalents. Projected production rate of 225,000 oz Au and 2,500,000 oz Ag annually.

Geology: Alteration comments: upper ore zone: argillization, silicification, manganese alteration. Alteration has resulted in the formation of clay and sericite along fractures and within the more permeable beds. Locally, complete replacement of the carbonate to form jasperoid has occurred along bedding and along some structures. Abundant manganese (as Mn-calcite) has been introduced into the rock, giving the clay and jasperoid a sooty brown appearance. Lower ore zone: base metal sulfides and pyrite were introduced into the host rock, filling fractures and partially replacing the host rock. Geology comments: the post-mineral caetano tuff (32-34 ma) covers +/- 60% of the cove deposit.

Rock formation(s): Favret Formation;Panther Canyon Formation;Augusta Mountain Formation


Ore(s): Fractures, Faults

References

Other Databases

Link to USGS MRDS:	10085018