| Quadrangle map, 1:250,000-scale | SI |
|---|---|
| Quadrangle map, 1:63,360-scale | D-3 |
| Latitude | 57.9095 |
| Longitude | -134.9902 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | The Kaiser Gypsum Mine is at an elevation of about 80 feet on an unnamed north tributary of Gypsum Creek. The mine is in the SE1/4 sec. 2, T. 46 S., R. 64 E. It is location P-21 of Bittenbender and others (1999), MAS no. 0021140041 (U.S. Bureau of Land Management, 2002). The location is accurate. |
Geologic descriptionThe rocks in the vicinity of the Kaiser Gypsum Mine are part of the Mississippian, Iyoukeen Formation (Lathram and others, 1965). The upper half of the formation is fossiliferous cherty limestone; the lower half is fossiliferous shale with minor limestone. A Cretaceous hornblende-biotite quartz monzonite stock is about 1.5 miles north of the mine.
The deposit was discovered in 1902 and was soon acquired by Pacific Coast Gypsum who developed it with two shafts, a raise, and 3,500 feet of drifts to a depth of 300 feet (Wright and Wright, 1907; Burchard, 1920; Steward, 1932; Flint and Cobb, 1953; Bittenbender and others, 1999). They operated the property from 1906 to 1923 and produced about 500,000 tons of gypsum. In 1923, the mine flooded and closed. It is unclear, however, whether it closed because it had exhausted the deposit and the company decided to stop pumping a wet mine or the flooding made the deposit uneconomic. Roppell (1973) has a particularly informative history of the discovery of the deposit, the personalities and companies involved, and the history of mining to the end of production. The deposit is on 6 patented claims that were acquired by Kaiser Gypsum Company in the late 1950s. The deposit was drilled by the U.S. Bureau of Mines in the 1960s. Unpublished data from industry in the office of the U.S. Bureau of Land Management in Juneau, Alaska, indicate that a reserve of 4.5 million tons of gypsum may remain (Bittenbender and others, 1999). The origin of the deposit is unclear and most people who have described it are uncertain whether it is a bedded syngenetic deposit or an epigenetic deposit related to a nearby quartz monzonite intrusion (Wright and Wright, 1907; Burchard, 1920; Steward, 1932; Flint and Cobb, 1953; Bittenbender and others, 1999). At least locally, the deposit is underlain by limestone breccia and overlain by conglomerate. Solution cavities filled with gravel are common. The structure of the deposit is complex with much folding and faulting, and the gypsum is deformed. The deposit is cut by thin basaltic dikes. At the 300 level of the mine, the workings covered an area about 600 by 800 feet and at the 160-foot level, the workings were about 500 by 1000 feet. An anhydrite vein 6 inches to more than 10 feet thick was found on the 160-foot level. | |
| Geologic map unit | (-134.991983285047, 57.9091612536838) |
|---|---|
| Mineral deposit model | Gypsum of debatable origin. |
| Age of mineralization | If sedimentary, the gypsum is Mississippian, the age of the formation that hosts it. If epigenetic, the gypsum may be related to nearby Cretaceous quartz monzonite. |
| Workings or exploration | The deposit was discovered in 1902 and was soon acquired by Pacific Coast Gypsum who developed it with two shafts, a raise, and 3,500 feet of drifts to a depth of 300 feet (Wright and Wright, 1907; Burchard, 1920; Stewart, 1932; Flint and Cobb, 1953; Bittenbender and others, 1999). In 1923, the mine flooded and closed. It is unclear however, whether it closed because it had exhausted the deposit and the company decided to stop pumping a wet mine or the flooding made the deposit uneconomic. The deposit was drilled by the U.S. Bureau of Mines in the 1960s. |
|---|---|
| Indication of production | Yes; medium |
| Reserve estimates | Unpublished data from industry in the files of the U.S. Bureau of Land Management in Juneau, Alaska, indicate that a reserve of 4.5 million tons of gypsum may remain (Bittenbender and others, 1999). |
| Production notes | Pacific Coast Gypsum operated the mine from 1906 to 1923 and produced about 500,000 tons of gypsum. Roppell (1973) has a particularly informative history of the discovery of the deposit, the personalities and companies involved, and the history of mining to the end of production. |
Additional commentsThe deposit is on six patented claims that were acquired by Kaiser Gypsum Company in the late 1950s. | |
ReferencesBittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
Gnagy, W L., 1962, Some notes on, and a tentative summary of, the genesis of the gypsum deposits at the Pacific Coast Mine, Gypsum Creek and Gypsum Camel, Iyoukeen Cove, Chichagof Island, southeast Alaska: Unpublished petrographic report, No. 2-43, U. S. Bureau of Mines, 5 p. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska.)
Gustafson, F.D., 1946, Preliminary report on the geology of Camel Gypsum, Alaska: Alaska Territorial Dept. of Mines Miscellaneous Report 114-6, 5 p.
Redman, Earl, 1989, Mining gypsum at Iyoukeen Cove: Unpublished report, 5 p. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska.)
Roppel, Patricia, 1973, Gypsum: Alaska Journal, V. 3, no. 3, p. 149-152.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1915: U.S. Bureau of Mines Bulletin 142, 65 p.
Smith, S.S., 1917, The mining industry in the Territory of Alaska during the calendar year 1916: U.S. Bureau of Mines Bulletin 153, 89 p.
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
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| Reporters | Donald Grybeck (U.S. Geological Survey) |
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| Last report date | 5/5/2005 |