Red Diamond Prospect, Juneau Mining District, Juneau, Alaska, USAi

Regional Level Types
Red Diamond Prospect	Prospect
Juneau Mining District	Mining District
Juneau	City Borough
Alaska	State
USA	Country

Location: 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.
Geology: 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.
Workings: 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).
Age: Newberry and others (1997) have interpreted this deposit as a Cretaceous volcanogenic massive sulfide deposit.
Alteration: Sericite.

Commodities (Major) - Ag, Au, Pb, Zn; (Minor) - Cu
Development Status: No
Deposit Model: Metamorphosed Kuroko massive sulfide deposit (Cox and Singer, 1986; model 28a)

Other Databases

Link to USGS - Alaska:	JU232

Other Regions, Features and Areas containing this locality

References