Location: The Mammoth prospect is at an elevation of approximately 1,000 feet on Nevada Creek, on Douglas Island. It is just south of the center of the north side of section 20, T. 42 S., R. 68 E. of the Copper River Meridian. The location is accurate.
Geology: The Mammoth prospect was discovered in the 1905 and was developed by 2 adits, each with 100 to 200 feet of workings (Redman and others, 1989). The prospect was explored by Hecla Mining Company in 1990 and 1991(Bundtzen and others, 1991; Swainbank and others, 1991). The prospect is in chlorite phyllite interbedded with lesser quartz-sericite phyllite, adjacent to a fault along Nevada Creek. Both phyllites contain 1 to 3 percent disseminated pyrite. U.S. Bureau of Mines samples contained up to 0.5 ppm gold, 9.3 ppm silver, 730 ppm copper, 3,580 ppm lead, and 860 ppm zinc (Redman and others, 1989). The deposit is similar to the Alaska Treasure Mine (JU228), Yakima (JU207), Red Diamond (JU232), and Homestake prospects (JU231), which Newberry and others (1997) interpret as Cretaceous volcanogenic massive sulfide deposits. Southeastern Douglas Island is underlain mainly by Upper Jurassic to mid-Cretaceous, marine argillite and graywacke, interbedded with basaltic volcanic and volcaniclastic rocks (Brew and Ford, 1985). The strata are regionally metamorphosed to prehnite-pumpellyite or greenschist grade.
Workings: The deposit at the Mammoth prospect was discovered in the 1905 and was developed by 2 adits, each with 100 to 200 feet of workings. The prospect was explored by Hecla Mining Company in 1990 and 1991(Bundtzen and others, 1991; Swainbank and others, 1991).
Age: Newberry and others (1997) have interpreted this deposit as a Cretaceous volcanogenic massive sulfide deposit.
Alteration: Sericite.

Commodities (Major) - Ag, Au, Cu, Pb, Zn
Development Status: None
Deposit Model: Metamorphosed Kuroko massive sulfide deposit (Cox and Singer, 1986; model 28a)

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

ⓘ Pyrite

1 valid mineral.

Detailed Mineral List:

ⓘ Pyrite

Formula: FeS₂

References:

(2008) Alaska Resource Data File (ARDF) Open-File Report 2008-1225. US Geological Survey

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
ⓘ	Pyrite	2.EB.05a	FeS₂

List of minerals for each chemical element

S	Sulfur
S	ⓘ Pyrite	FeS₂
Fe	Iron
Fe	ⓘ Pyrite	FeS₂

Other Databases

Link to USGS - Alaska:	JU229

Other Regions, Features and Areas containing this locality

North AmericaContinent

Coast MountainsMountain Range

North America PlateTectonic Plate

Taku DomainDomain
Yukon-TananaVolcanic Arc

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Brew, D.A., and Ford, A.B., 1985, Preliminary reconnaissance geologic map of the Juneau, Taku River, Atlin, and part of the Skagway 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 85-395, 23 p., 2 sheets, scale 1:250,000. Bundtzen, T.K., Swainbank, R.C., Wood, J.E., Clough, A.H., 1991, Alaska's Mineral Industry 1991: Alaska Division of Geological & Geophysical Surveys, Special Report 46, 89 p. Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150. Redman, E.C., Maas, K.M., Kurtak, J.M., and Miller, L.D., 1989, Bureau of Mines Mineral Investigations in the Juneau Mining District, Alaska, 1984-1988, Volume 2--Detailed mine, prospect, and mineral occurrence descriptions, Section D, Juneau Gold Belt Subarea: U.S. Bureau of Mines Special Publication, 424 p. Swainbank, R.C., Bundtzen, T.K., and Wood, J.E., 1991, Alaska's mineral industry, 1990: Alaska Division of Geological and Geophysical Surveys Special Report 45, 78 p.

Quick NavTop Commodities Mineral List Other Databases Other Regions References

Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: October 21, 2026 15:35:12 Page updated: July 15, 2025 01:59:10

Go to top of page