Ophir

Prospect, Active

Alternative names

Hartford
Chilkat
Selkirk
Acropolis

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale JU
Quadrangle map, 1:63,360-scale D-4
Latitude 58.8696
Longitude -135.0983
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Ophir prospect ( or 'mine' as it is commonly called even though it has no production) is at an elevation of about 1,450 feet, 2 miles northeast of Pt. Sherman on Lynn Canal and 1 mile west-southwest of Lions Head Mountain in the Kakuhan Range. The 'Ophir Mine' is marked on the Juneau D-4 topographic map. It is approximately 3/4 mile northwest of the Kensington Mine (JU029), in the NE1/4 section 5, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

Note: Beginning in the 1990s, this and other old mines and prospects in the vicinity were consolidated by Coeur-Alaska into a single property (Birak, 2006). They have carried out major new drilling and underground exploration that better defines the mineralization, largely blurs the geologic distinction among the old deposits, and extends the ore bodies greatly. They have developed a coherent modern interpretation of the mineralization as a single deposit which Coeur-Alaska intends to mine as a unit. This deposit is described separately in ARDF as the Kensington (Coeur-Alaska) deposit (JU261). For geologic reference purposes and for their historic value, the pre-Coeur-Alaska data for this and the other old mines and prospects that Coeur-Alaska consolidated are retained in ARDF.
The Ophir prospect consists of several quartz veins and associated quartz-vein stockwork in Jualin Diorite. The Ophir deposit was discovered in 1887; the workings consist of a 350-foot adit with 250 feet of drifts, a 125-foot adit with a 75-foot crosscut, and a 75-foot inclined shaft (Redman and others, 1989). The Ophir workings explored at least 5 quartz veins, the Hartford, Ophir, Chilkat, Selkirk, and Acropolis (Kensington Mines, 1914).
Geologic map unit (-135.100120746466, 58.8692695479929)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold-quartz-vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
Alteration of deposit Hydrothermal alteration adjacent to the veins is characterized by reddish-brown ferroan dolomite alteration (Miller and others, 1995). Other alteration includes sericitization of plagioclase, chloritization and sulfidization of mafic minerals, and albitization of feldspars (Leveille, 1991).

Production and reserves

Workings or exploration The Ophir deposit was discovered in 1887. Workings consist of a 350-foot adit with 250 feet of drifts, a 125-foot adit with a 75-foot crosscut and a 75-foot inclined shaft (Redman and others, 1989). The deposit has been explored by Placid Oil Co. and Echo Bay Mines/Coeur-Alaska, and in 2001 is controlled by Coeur-Alaska.
Indication of production Undetermined

References

MRDS Number A012075

References

Birak, D.J., 2006, Kensington gold project: Unpublished Technical Report for Cour d'Alene Mines, 116 p. (posted on www/.sedar.com, April 20, 2006).
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Leveille, R.A., 1991, Geology and gold deposits of the Jualin mine area, Berners Bay district, southeastern Alaska: Fairbanks, University of Alaska, M.S. thesis, 200 p.
Miller, L.D., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation at the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, p. 343-368.
Reporters J.C. Barnett and L.D. Miller (Juneau, Alaska ); D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008