Red Diamond

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Pb; Zn
Other commodities Cu
Ore minerals chalcopyrite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale A-2
Latitude 58.2124
Longitude -134.3446
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Red Diamond prospect is at an elevation of approximately 1,300 feet on Douglas Island, just below and south of the divide between Nevada Creek and Stephens Passage, and 1 mile southeast of McDonough Peak. It is in the NE1/4SE1/4 section 19, T. 42 S., R. 68 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The Red Diamond prospect was discovered in 1902 and was developed by 5 adits, 4 shafts, and numerous trenches (Redman and others, 1989). Hecla Mining Company had a substantial core-drilling program at the Red Diamond prospect in 1990 and 1991. Drilling by Hecla during 1991 reportedly returned favorable results but Hecla decided to discontinue mineral exploration in Alaska in favor of exploration in Mexico and South America (Bundtzen and others, 1991; Swainbank and others, 1991). The deposit consists of massive greenstone with intercalated chlorite phyllite and quartz-mica schist (Redman and others, 1989). The phyllite is pale green and contains up to 5 percent disseminated pyrite cubes. Quartz stringers and concordant to locally discordant quartz veins are locally abundant and contain pyrite and minor chalcopyrite. The mineralized zone is approximately 35 feet thick, strikes northeast, and dips 70 SE. U.S. Bureau of Mines samples contained up to 13.7 ppm gold, 2.1 ppm silver, 620 ppm lead, and 955 ppm zinc (Redman and others, 1989). The deposit is similar to the Alaska Treasure mine (JU228), and the Mammoth (JU229), Yakima (JU207) and Homestake prospects (JU231), which Newberry and others (1997) interpret as Cretaceous volcanogenic massive sulfide deposits.
Southeastern Douglas Island is underlain mainly by Upper Jurassic to mid-Cretaceous, marine argillite and graywacke, interbedded with basaltic volcanic and volcaniclastic rocks (Brew and Ford, 1985). The rocks are regionally metamorphosed to prehnite-pumpellyite or greenschist grade.
Geologic map unit (-134.346364850744, 58.2120695214337)
Mineral deposit model Metamorphosed Kuroko massive sulfide deposit (Cox and Singer, 1986; model 28a)
Mineral deposit model number 28a
Age of mineralization Newberry and others (1997) have interpreted this deposit as a Cretaceous volcanogenic massive sulfide deposit.
Alteration of deposit Sericite.

Production and reserves

Workings or exploration The Red Diamond prospect was discovered in 1902 and was developed by 5 adits, 4 shafts, and numerous trenches (Redman and others, 1989). Hecla Mining Company had a substantial core-drilling program at the Red Diamond in 1990 and 1991. Drilling by Hecla Mining Company during 1991 reportedly returned favorable results, but Hecla decided to discontinue mineral exploration in Alaska in favor of exploration in Mexico and South America (Bundtzen and others, 1991; Swainbank and others, 1991).
Indication of production None

References