|Quadrangle map, 1:250,000-scale||JU|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Ivanhoe Mine is at an elevation of about 2,300 feet, in the Kakuhan Range, 2 miles northeast of Pt. Sherman on Lynn Canal and 1 mile west of Lions Head Mountain. The mine is marked on the Juneau D-4 topographic map. It is in the NE1/4 section 32, T. 34 S., R. 62 E. of the Copper River Meridian. The location is accurate.|
The Ivanhoe Mine was discovered in 1896. In 1897, a 20-stamp mill was installed and a 5,700-foot tramway was constructed. By 1902, the mine had produced 340 ounces of gold from 3,500 tons of ore. The mine has 1,100 feet of workings and 2 stoped areas, 6 adits, 1 crosscut, and a 100-foot shaft.
The Ivanhoe mine developed a quartz vein entirely contained in metamorphosed basalt, unlike most other veins in the Berners Bay district, which are typically are hosted in Jualin Diorite. The vein trends northerly to northwesterly and dips 35 to 55 East. It varies from 1 foot to 9 feet thick and has been traced on the surface for 1,500 feet along strike. The contact between the vein and the metabasalt is sheared and fragments of basalt are common in the vein. Pyrite and chalcopyrite occur in the vein as small clots or thin bands. Native copper occurs in the deeper stopes as dendrites on fractures in the quartz. This is the only occurrence of native copper in the Juneau Gold Belt (Redman and others, 1989). U.S. Bureau of Mines samples contained up to 0.14% copper and 15 ppm gold. Their weighted average over 4.3 feet was 2.3 ppm gold and 5.9 ppm silver. (Redman and others, 1989).The Ivanhoe Mine is within the Berners Bay district at the north end of the Juneau Gold Belt. The district is characterized by a series of structurally-controlled mesothermal, gold-bearing quartz veins. Most of the veins cut the Lower Cretaceous Jualin Diorite, which intrudes Mesozoic (Upper Triassic) metabasalt (Miller and others, 1995). The age of mineralization in the Berners Bay area is about 55 Ma, the same as the other mesothermal gold vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
|Geologic map unit||(-135.104721295183, 58.8819693605484)|
|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).|
|Workings or exploration||The Ivanhoe Mine was discovered in 1896. In 1897, a 20-stamp mill was installed and a 5,700-foot tramway was constructed. The mine has 1,100 feet of workings and 2 stoped areas, 6 adits, 1 crosscut and a 100-foot shaft.|
|Indication of production||Yes; small|
|Reserve estimates||The Ivanhoe Mine has a resource of 180,000 tons of ore that contains 0.7 ounce of gold per ton and 0.2 ounce of silver per ton (Redman and others, 1989).|
|Production notes||By 1902, the mine had produced 340 ounces of gold from 3,500 tons of ore.|
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.
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.
Redman, E.C., Maas, K.M., Kurtak, J.M., and Miller, L.D., 1991, Section D: Juneau Gold Belt subarea, in U.S. Bureau of Mines, Mineral investigations in the Juneau Mining District, Alaska, 1984-1988: Volume 2 - Detailed mine, prospect, and mineral occurrence descriptions: U.S. Bureau of Mines Special Publication VOL. 2D, 424 p., 19 sheets.
|Reporters||J.C. Barnett and L.D. Miller (Juneau, Alaska )|
|Last report date||12/15/2001|