Makushin Valley SE Occurrence, Aleutians District, Aleutians West Borough, Alaska, USA
Location: Southeast side of Makushin Valley. Anomaly no. 6 of Christie (1974).
Geology: Color anomaly in Unalaska Formation (see Drewes and others, 1961) associated with porphyritic diorite. Diorite is weakly altered, contains miarolitic cavities, less than 0.5 percent pyrite and more than 2 percent magnetite. Fracturing is local strongly developed ans strikes east and northeast. No chalcopyrite seen. Zone containing more than 2 percent pyrite is roughly 600 ft (180 m) by 4,000 ft (1220 m).
Workings: Single sample reported, reconnaissance mapping. Sample showed 90 ppm copper and 1.4 ppm silver.
Alteration: Possibly propylitic and argillic alteration. Partial leaching, fractures largely leached.
Commodities (Major) - Cu; (Minor) - Ag
Development Status: No
Deposit Model: Copper porphyry
ReferencesChristie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.) Drewes, Harold, Fraser, G.D., Snyder, G.L., and Barnett, H.F., Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-S, p. 583-676.
| Magnetite|| Pyrite|
2 entries listed. 2 valid minerals.
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