Mount Hurst

The Mount Hurst 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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Site Name

Primary: Mount Hurst

Commodity

Primary: Chromium

Location

State: Alaska
District: Ophir

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

Not available

Analytical Data

Not available

Materials

Ore: Chromite
Ore: Spinel

Comments

Comment (Deposit): Model Name = Podiform chromite (Cox and Singer, 1986; model 8a)

Comment (Workings): Workings / Exploration = The U.S. Bureau of Mines first investigated Mt. Hurst as a potential source of chromic oxide and platinum-group metals in 1981. Since then, there have been staking and minor exploration programs by private interests.

Comment (Reference): Primary Reference = Roberts, 1984

Comment (Deposit): Other Comments = See also Boob Creek (OP013).

Comment (Geology): Geologic Description = Mt. Hurst is composed of chromite- and chrome spinel-bearing ultramafic rocks surrounded by lower Paleozoic crystalline limestone, schist, slate, phyllite, quartz, and chert. A nearby upper Paleozoic sequence of greenstone, metavolcanic rocks, tuff, and chert-bearing sedimentary rocks suggests a possible ophiolitic origin for the ultramafic rocks (Roberts, 1984). The ultramafic rocks at Mt. Hurst are crudely layered; certain layered zones are traceable for more than 2 miles. Rock types include dunite, wehrlite, harzburgite, lherzolite, and clinopyroxenite. One outcrop of dunite has been altered to carbonate, quartz, and talc. At least two minor occurrences of basalt and one outcrop of gabbro are also present (Roberts, 1984). Chromitite samples collected from the Mt. Hurst area are anomalous in platinum (0.014 - 0.026 ounce per ton) and palladium (0.003 ounce per ton). Wehrlite samples also contained minor amounts of platinum. Altered dunite samples contained elevated concentrations of mercury, antimony, arsenic, and silver. Coalescent or banded chromite is present almost exclusively within dunite layers in wehrlite (Roberts, 1984). Heavy-mineral concentrates panned from three separate drainages on the flanks of Mt. Hurst respectively contained 1474 ppb platinum, 1508 ppb platinum, and 2674 ppb gold (Roberts, 1984). The largest chrome spinel occurrence in the Mt. Hurst area is at this site (Roberts, 1984, locality 10). It is in a chromite band in a light orange-brown dunite lens in well-layered, light-green wehrlite. The chromite band trends northeast for about 30 feet; the southern end disappears beneath vegetation, soil and talus. It pinches and swells from 6 to 30 inches thick over 30 feet. Concentrations of chrome spinel within the chromite band vary from 30 to 80% of the rock. Chromitite samples from this locality contain about 30% chromic oxide (Roberts, 1984). The chrome spinel occurrences on Mt. Hurst appear to be very sparse and variable in size and quality. The presence of detectable platinum and palladium in sediments shed from the ultramafic rocks at Mt. Hurst (see Boob Creek, OP013) suggests a potential for paleo-placers (Roberts, 1984).

References

Reference (Deposit): Roberts, W.S., 1984, Economic potential for chromium, platinum, and palladium in the Mount Hurst ultramafics, west-central Alaska: U.S. Bureau of Mines Open-File Report 84-22, 52 p.

Reference (Deposit): Foley, J.Y., Burns, L.E., Schneider, C.L., and Forbes, R.B., 1989, Preliminary report of platinum group element occurrences in Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 89-20, 32 p., 1 map sheet, scale 1:2,500,000.

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