Lansing

Mine, Inactive

Alternative names

Hidden Treasure
Homestake 1-4
Blue Fox group

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Pb; Zn
Ore minerals arsenopyrite; galena; gold; pyrite; sphalerite
Gangue minerals calcite; chlorite; graphite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-4
Latitude 60.8721
Longitude -148.3796
Nearby scientific data Find additional scientific data near this location
Location and accuracy The mine is located 2,000 feet inland from the head of Pigot Bay between 400 and 700 feet elevation. It is located in the NW 1/4 section 15, T. 9 N., R. 6 E., of the Seward Meridian. The Lansing mine symbol is mislocated on the USGS topographic map. This is location 128 of Condon and Cass (1958), location 61 of Cobb and Richter (1972), location 85 of MacKevett and Holloway (1977), location 135 of Cobb and Tysdal (1980), and S-164 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The bedrock in the mine area is phyllite and slate of the Valdez Group of Late Cretaceous age. The rocks have been deformed by the Port Wells fault, which is a northeast-trending regional shear zone (Nelson and others, 1985). Several boulders of felsic igneous rocks occur near the mine, but there is no evidence that they are related to the deposit.
The deposit consists of several quartz veins that locally contain varying amounts of arsenopyrite, pyrite, galena, sphalerite, and gold. Other gangue minerals locally include calcite, chlorite, and graphite. The principal veins are numbered 1-3. Mining has occurred on the No. 1 vein, which crops out at about 550 feet elevation, and on the No. 2 vein, which is only exposed in the workings. The No. 3 vein, exposed at an elevation of 1,600 foot, is on strike with the No. 1 vein; it may an extension of the No. 1 vein (Roehm, 1938 [PE 95-12]). In the main drift, the No. 1 vein forms discontinuous lenses and pods. One lens in the main drift was 50 feet in length and ranged in width from a few inches to 18 inches. The quartz is banded, folded, and curled and contains graphite bands that carry the greatest gold values (Roehm, 1938). Roehm reported that this lens assayed $43 in gold per ton in the drift and $100.00 in gold per ton on the surface (gold at $20.67 per ounce). Roehm (1938) examined thin sections of this vein and identified two distinct generations of quartz. The early quartz is milky white and forms large crystals having distinct faces. The later quartz is bluish and finer grained and shows indistinct crystal faces; it also contains abundant wallrock inclusions that have a curled appearance. Associated with the younger quartz are calcite and chlorite and extremely fine grained sulfides including arsenopyrite, galena, and sphalerite, along with a little gold (Roehm, 1938).
The No. 2 vein was discovered when the main adit was being driven and consists of 6 to 8 inches of quartz. This vein is not exposed on the surface. A 25-foot drift was driven on this vein, which strikes N50E and dips 60NW. The U.S. Bureau of Mines sampled this vein in 1979 and reported no detectable gold or silver (Hoekzema and Sherman, 1983).
The No. 3 vein is exposed at 1,600 feet above sea level and is intermittently exposed for about 700 feet. The general strike of the vein is northeast, and it dips 50 to 60 NW. The vein is 6 to 10 inches wide; auriferous sulfides occur as pods and kidneys. Average values of $100 of gold per ton were reported (gold at $20.67 per ounce). A 140-foot-long crosscut was driven below the vein, but whether it intersected the vein is not reported (Roehm, 1938).
The recorded production from all the workings is 81 ounces of gold and 24 ounces of silver (Jansons and others, 1984).
Geologic map unit (-148.381691749845, 60.8715112277455)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Tertiary or younger; the veins are associated with the Port Wells fault, which northeast of the mine cuts Tertiary granitic rocks.
Alteration of deposit Roehm (1938 [PE 95-12]) reported that the country rock is considerably altered but did not describe whether the alteration is mechanical due to tectonics or hydrothermal due to veining.

Production and reserves

Workings or exploration
The working on the various veins are as follows: A 90-foot crosscut intersects the No. 1 vein, which was followed by drifting along strike for 110 feet. This drift was stoped upward for 5 to 10 feet. The No. 2 vein was followed by drifting for 30 feet. A crosscut was started to intersect the No. 3 vein, but not driven far enough to intersect it. There are also numerous open cuts and shallow shafts on the No. 1 and No. 3 veins (Hoekzema and Sherman, 1983).
During the 1930s, Superior Mines, Inc. constructed a small mill complex below the workings. It consisted of a crusher, 3 by 4 ball mill, hydraulic classifier, flotation cells, and a Gibson amalgamator. The ore was transported to the mill by a jig-back aerial tram. Power was supplied to the mill by a 20-horsepower Fairbanks-Morse diesel motor. The mine was powered by a R40 Ingersoll-Rand 3-stage compressor run by a 40-horsepower Fairbanks Morse diesel motor (Roehm, 1938 [PE 95-12]).
During 1979, the U.S. Bureau of Mines visited the mine and collected eight grab samples from the workings. These samples assayed from 0 to 3.9 ppm gold, the best values coming from the stope on the No. 1 vein.
Indication of production Yes; small
Reserve estimates The U.S. Bureau of Mines estimated a geologic resource of 500 tons of ore with a grade of 0.1 ounce of gold per ton and 0.02 ounce of silver per ton (Hoekzema and Sherman, 1983).
Production notes Recorded production from this property is 81 ounces of gold and 24 ounces of silver (Jansons and others, 1984).

Additional comments

The recorded production from this mine shows a gold-to-silver ratio of 3.4:1, whereas assay results are closer to 10:1. Most of the mines in this district also show gold-to-silver ratio of about 10:1.

References

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 2/22/2000