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Broken Ridge Mining District, Iron County, Utah, USAi
Regional Level Types
Broken Ridge Mining DistrictMining District
Iron CountyCounty
UtahState
USACountry

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Type:
Mining District
Mindat Locality ID:
418291
Long-form identifier:
mindat:1:2:418291:0
GUID (UUID V4):
0


The Broken Ridge mining district is located about 40 miles northwest of Cedar City in northwestern Iron County. The area’s mineral potential was not recognized until the 1970s. Broken Ridge has no history of mineral production, but the area has been prospected for alunite, U, Mo, and Sn.

Broken Ridge is situated in a low range of mountains northwest of the Escalante Desert in the Basin and Range Province. Mineralization is related to Miocene bimodal magmatism and the onset of extension and continental rifting. This magmatism, in conjunction with a series of northeast-trending normal and strike-slip faults, developed in a northeast-trending zone from Modena to Milford. This zone, which includes the Bible Springs fault zone, has coeval rhyolitic plugs, dikes, and flow domes of the Steamboat Mountain Formation (~12 Ma) which unconformably overlies tilted/rotated Oligocene volcanics and older rocks. Geochemical levels of Mo, Sn, and other lithophile elements are reported from stream sediment samples covering a 19-sq-mi area around Broken Ridge (Tucker and others, 1981; Duttweiler and Griffitts, 1989).

A 3 mile diameter, cauldron-like depression, covering the southern end of Broken Ridge is filled with Steamboat Mountain Formation rhyolite. The large Mountain Spring rhyolite dome straddles the southern margin of this cauldron-like feature. Steamboat Mountain rhyolite phenocrysts at Broken Ridge are typically smoky quartz, sanidine, plagioclase, and minor biotite.

Compositionally, the leucocratic alkali rhyolites average just over 75% SiO2, 4.8% K2O, and 1100 ppm F, and are garnet- and topaz-bearing. The petrochemistry of these rhyolites is like that of Climax porphyry Mo systems. Scattered areas of argillic and advanced argillic alteration of the Steamboat Mountain Formation occur along the Bible Springs fault zone and on Broken Ridge, particularly near the Mountain Spring dome. Rock-chip samples from the Broken Ridge area, chiefly near the Mountain Spring dome, are strongly anomalous in Mo, Sn, W, B, Be, Bi, F, Li, Mn, Pb, Sb, Th, U, and Zn (Tucker and others, 1981; Duttweiler and Griffitts, 1989).

The Broken Ridge area displays some of the characteristics expected at the top of a porphyry Mo system including: (1) the petrochemistry of the rhyolites on Broken Ridge, (2) a strong rock-chip lithophile geochemical signature, (3) extensive hydrothermal alteration at the surface, and (4) the presence of the large Mountain Spring dome suggesting a cupola at depth.

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Mineral List

Mineral list contains entries from the region specified including sub-localities

3 valid minerals.

Rock Types Recorded

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List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘHematite4.CB.05Fe2O3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
ⓘAlunite7.BC.10KAl3(SO4)2(OH)6
Group 9 - Silicates
ⓘKaolinite9.ED.05Al2(Si2O5)(OH)4

List of minerals for each chemical element

HHydrogen
Hⓘ AluniteKAl3(SO4)2(OH)6
Hⓘ KaoliniteAl2(Si2O5)(OH)4
OOxygen
Oⓘ AluniteKAl3(SO4)2(OH)6
Oⓘ HematiteFe2O3
Oⓘ KaoliniteAl2(Si2O5)(OH)4
AlAluminium
Alⓘ AluniteKAl3(SO4)2(OH)6
Alⓘ KaoliniteAl2(Si2O5)(OH)4
SiSilicon
Siⓘ KaoliniteAl2(Si2O5)(OH)4
SSulfur
Sⓘ AluniteKAl3(SO4)2(OH)6
KPotassium
Kⓘ AluniteKAl3(SO4)2(OH)6
FeIron
Feⓘ HematiteFe2O3

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USA

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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

Tucker, J.D., Miller, W.R., Motooka, J.M., Hubert, A.E. (1981) A geochemical investigation of a known molybdenum-tin anomaly in southwestern Utah. U.S. Geological Survey Open-File Report 81-576, 77 pages.
Duttweiler, K.A., Griffitts, W.A. (1989) Geology and geochemistry of the Broken Ridge area, southern Wah Wah Mountains, Iron County, Utah. U.S. Geological Survey Bulletin 1843, 32 pages.
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