Unnamed Occurrence (ARDF - BC011), Petersburg District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA

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This occurrence is in Misty Fiords National Monument
Location: This unnamed occurrence is located at an elevation of about 3350 feet a few hundred feet upslope from a small (0.1 mile diameter) unnamed lake on a northwest-trending ridge drained by east-flowing tributaries to the lower Hulakon (Eulachon) River (Elliott and Koch, 1981, p. 8, loc. 11). The location is accurate to within about a quarter of a mile.
Geology: The country rocks in the general area of this occurrence are Mesozoic or Paleozoic paragneiss and orthogneiss, and subordinate amphibolite and marble (Elliott and Koch, 1981; Koch, 1997). The mineral occurrence consists of small, irregular pods of garnet-diopside skarn containing 1% disseminated molybdenite (Elliott and Koch, 1981, loc. 11). The skarn, which is accompanied by calc-silicate rock, forms pods and discontinuous disrupted layers(?) in amphibolite. The molybdenite occurs as minute discrete flakes in the skarn, and in and near glassy quartz veinlets (Koch, 1997, p. 31). Pelitic paragneiss about 1.5 miles north of this occurrence contains disseminated minute flakes of molybdenite, and geochemically anomalous Ag and Sn (Koch, 1997, p. 31). Koch (1997, p. 30-32) also reports anomalous values of Ag, Au, Cu, Mo, Sn, and Zn in a few geochemical samples collected by the U. S. Geological Survey in the late 1970's near this occurrence.
Workings: Pelitic paragneiss about 1.5 miles north of this occurrence contains disseminated minute flakes of molybdenite, and geochemically anomalous Ag and Sn (Koch, 1997, p. 31). Koch (1997, p. 30-32) also reports anomalous values of Ag, Au, Cu, Mo, Sn, and Zn in a few geochemical samples collected in the area near this occurrence by the U.S.Geological Survey in the late 1970's.
Alteration: Formation of calc-silicate skarn in amphibolite country rock

Commodities (Major) - Mo
Development Status: None
Deposit Model: Skarn

References

Elliott, R.L., and Koch, R.D., 1981, Mines, prospects, and selected metalliferous mineral occurrences in the Bradfield Canal quadrangle, Alaska: U.S. Geological Survey Open-File Report 81-728-B, 23 p., 1 sheet, scales 1:250,000 and 1:63,360. Koch, R.D., 1996 [In press), Reconnaissance geologic map of the Bradfield Canal quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report, 1 sheet, scale 1:250,000. Koch, R.D., 1997 [in press], Metalliferous mineral resource potential in the Bradfield Canal quadrangle, southeastern Alaska: U.S. Geological Survey Open-File Report, 1 sheet, scale 1:250,000.

Mineral List

Diopside

'Garnet'

Molybdenite

Quartz

4 entries listed. 3 valid minerals.