The Unnamed (east of hill 2120) is a chromium mine located in Alaska.
About the MRDS Data:
All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.
Mine Info
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Unnamed (east of hill 2120) MRDS details
Site Name
Primary: Unnamed (east of hill 2120)
Commodity
Primary: Chromium
Location
State: Alaska
District: Kaiyuh
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Not available
Deposit
Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:
Physiography
Not available
Mineral Deposit Model
Model Name: Podiform chromite (minor)
Orebody
Not available
Structure
Not available
Alterations
Not available
Rocks
Role: Host
Age Type: Host Rock
Age Young: Jurassic
Analytical Data
Not available
Materials
Ore: Chromite
Comments
Comment (Reference): Primary Reference = Foley and others, 1984
Comment (Geology): Age = Jurassic, the age of the ultramafic hostrocks (Patton and others, 1977).
Comment (Exploration): Status = Inactive
Comment (Geology): Age = Host rock is Jurassic.
Comment (Deposit): Model Name = Podiform chromite (Cox and Singer, 1986; model 8a)
Comment (Workings): Workings / Exploration = Chromite occurrences within the Kaiyuh Hills were first documented in 1980 by C.C. Hawley and Associates, Inc., during their investigations for Armco Mineral Exploration, Ltd. The U.S. Bureau of Mines examined four of the occurrences in 1982 and published a report in 1984 (Foley and others, 1984).
Comment (Geology): Geologic Description = Chromite occurrences in the Kaiyuh Hills were first documented in 1980 by C.C. Hawley and Associates, Inc., during their investigations for Armco Mineral Exploration, Ltd. The Bureau of Mines examined four of the occurrences in 1982, and published a report in 1984 (Foley and others, 1984). Twenty-one occurrences were located within a northeast-trending, approximately 6-mile-long body of dunite and pyroxene peridotite in the Kaiyuh Hills. The largest 4 occurrences are described in this record and in records NL003, 004, and 005. These four occurrences are estimated to contain a combined total of between 17,000 and 37,000 tons of chromic oxide (Foley and others, 1984).? the Kaiyuh Hills are underlain by a portion of the Rampart ophiolite belt that is offset along the Kaltag fault from the remainder of the belt. The belt comprises two tectonic units: an upper unit of ultramafic and gabbroic rocks and a lower unit of mafic volcanic rocks, diabase, and chert (Patton and others, 1977). Ultramafic rocks of the upper unit, which contain the chromite occurrences, are exposed along a 24-mile-long, northeast-striking belt in the Kaiyuh Hills (Foley and others, 1984). At the southwestern end of the belt is a 6-square-mile area underlain mostly by a body of dunite. This dunite contains more than 90% olivine, sparsely disseminated chromite, and locally banded segregations of disseminated to massive chromite. Nodular chromite was observed at one location. At the northeastern end of this body, the dunite grades into pyroxene peridotite interlayered with dunite. This part of the body also contains chromite bands ranging in thickness from less than 1 inch to 3 feet. The dunite layers range from a few inches to several hundred feet thick. The pyroxene peridotite is mostly harzburgite. Minor amounts of wehrlite and lherzoliteare also present (Foley and others, 1984).? This occurrence consists of a 75- by 300-foot zone of discontinuous bands of chromite up to 2.5 inches thick and 1.5 feet long. The chromite occurs as highly fractured, subhedral to anhedral crystals disseminated in serpentinized dunite. Fractures in the chromite are filled with pale green serpentine. Chalky white to pale blue magnesite coats weathered surfaces (Foley and others, 1984). This zone contains approximately 3% chromite, and is estimated to contain between 3,000 and 6,000 tons of chromic oxide (Foley and others, 1984).
Comment (Reserve-Resource): Reserves = This occurrence is estimated to contain between 3,000 and 6,000 tons of chromic oxide. This occurrence and three others nearby (NL003, 004, and 005) contain a combined total of between 17,000 and 37,000 tons of chromic oxide.
References
Reference (Deposit): Patton, W.W. Jr., Tailleur, I.L., Brosge, W.P., and Lanphere, M.A., 1977, Preliminary report on the ophiolites of northern and western Alaska: Oregon Department of Geologic and Mineral Industry Bulletin 95, p. 51-57.
Reference (Deposit): Foley, J.Y., Hinderman, T., Hawley, C.C., Kirby, D.E., and Mardock, C.L., 1984, Chromite occurrences in the Kaiyuh Hills, west-central Alaska: U.S. Bureau of Mines Open-File Report 178-84, 20 p.
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