Unnamed Occurrence (ARDF - TN079; on Serpentine Ridge; Boulder), Hot Springs Mining District, Yukon-Koyukuk Census Area, Alaska, USAi
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Latitude & Longitude (WGS84):
65° 7' 55'' North , 151° 4' 44'' West
Latitude & Longitude (decimal):
Köppen climate type:
Location: This site represents a chromite occurrence on locally-named Serpentine Ridge. For this record, the site is on a tractor trail at an elevation of about 1,500 feet, in the northeast quarter of section 31, T. 4 N., R. 17 W., of the Fairbanks Meridian. The location is accurate within a mile. This site is Cobb's (1972) location 4, and roughly corresponds with the U.S. Bureau of Land Management site for Boulder (MAS number 0020480001). The MAS report for Boulder also lists Mo and Au as commodities, but there are no reports of those metals at this site elsewhere in the literature.
Geology: The Boulder Creek area is underlain by Jurassic or Cretaceous clastic sedimentary rocks, which are intruded and contact metamorphosed by the Cretaceous monzodiorite and granite Roughtop Mountain pluton (Chapman and others, 1982; Reifenstuhl and others, 1998). Serpentine Ridge, on the south side of the creek, is upper Cretaceous(?) serpentinite, diabase, and gabbro that is in thrust-fault contact with the clastic sedimentary rocks. Moxham (1954) identified chromite float on the south slopes of the ridge between Woodchopper and Boulder creeks, and small lenses and stringers of chromite that are in place on the ridge top. Berg and Cobb (1967) reported chromite disseminated in serpentinite on Serpentine Ridge and pieces of chromite float up to 6 inches in diameter.
Workings: Moxham (1954) identified chromite float on the south slopes of the ridge between Woodchopper and Boulder creeks, and small lenses and stringers of chromite that are in place on the ridge top. Berg and Cobb (1967) reported chromite disseminated in serpentinite on Serpentine Ridge and pieces of chromite float up to 6 inches in diameter.
Age: Late Cretaceous?
Commodities (Major) - Cr
Development Status: None
Deposit Model: Podiform chromite (Cox and Singer, 1986; model 8a) or (metamorphosed) Bushveld
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
1 valid mineral.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Chromite | 4.BB.05 | Fe2+Cr3+2O4 |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Chromite | Fe2+Cr23+O4 |
| Cr | Chromium | |
| Cr | ⓘ Chromite | Fe2+Cr23+O4 |
| Fe | Iron | |
| Fe | ⓘ Chromite | Fe2+Cr23+O4 |
Other Databases
| Link to USGS - Alaska: | TN079 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Arctic AlaskaPassive Margin
- Wickersham DomainDomain
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