SK Star Claim #2, Thomas Range, Juab County, Utah, USAi
Regional Level Types | |
---|---|
SK Star Claim #2 | Claim (Active) |
Thomas Range | Mountain Range (Active) |
Juab County | County |
Utah | State |
USA | Country |
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Latitude & Longitude (WGS84):
39° 41' 7'' North , 113° 8' 44'' West
Latitude & Longitude (decimal):
Type:
Claim (Active) - last checked 2023
Deposit first discovered:
2015
Age:
23.03 to 5.332 Ma
Köppen climate type:
Mindat Locality ID:
435405
Long-form identifier:
mindat:1:2:435405:8
GUID (UUID V4):
d7ffaa1e-ced0-4c1d-baf6-d30e250b7027
The SK Star Claim #2 is a small BLM mine claim that is, as far as the owner as well as geologists that studied the site can tell, the only place on Earth that consistently produces black topaz. Originally discovered by Sean Rasmussen and Krisann Morrill in 2015 after they discovered some black material that was thought to be Obsidian at first. Further investigation revealed it to in fact to be euhedral crystals of dark black topaz, and upon realizing this, Rasmussen and Morrill immediately struck a claim. The pair continues to work the claim by hand, unearthing more specimens each year.
The mine itself is a trench, dug along a NW trending fault, which hosts the mineralization. The host rock is a vuggy section of the Topaz Mountain Rhyolites, which are associated with volcanism that occurred during the Miocene. The minerals found there include the Black Topaz, a mix of uncommon metal oxide minerals including Wolframite and Pseudobrookite, "Ram's Horn" Calcite, Uranium-Bearing Chalcedony, and rarely Native Gold.
The Topaz from the site is consistently euhedral and partially or completely black in color. Most samples are very small, less than 3 cm in length, but occasionally much larger crystals are found. Twinning and double termination are both quite common at the site. The crystals a black due to hundreds of microscopic inclusions that measure on average about 30 micrometers across. They are mostly Wolframite or Biotite, with compositional zonations observed inside some crystals.
Geologists at Western Carolina University, as part of a senior thesis by Patrick Lahr working with Sean Rasmussen, attempted to try to figure out a formational model. In the process, they were able to get XRF and ICP-MS measurements, as well as conduct a thin section petrographic analysis on samples from the site. Based on the data available, the working theory is that a fault ruptured during crystallization creating a pathway for fluids to interfere with the crystallization, depositing incompatible elements onto the surface of the crystal. The incompatible elements were subsequently incorporated into the crystal structure, which turned the crystals black in colour. This is still an ongoing project by Patrick Lahr, though now as independent research due to graduating. Samples from this project are maintained within the Marsh Fox Collection.
Additionally, the site has produced rather fine samples of highly fluorescent Uranium Bearing Chalcedony. XRF conducted by Western Carolina University measured the Uranium content to be 269 PPM.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsMineral List
6 valid minerals.
Rock Types Recorded
Note: data is currently VERY limited. Please bear with us while we work towards adding this information!
Select Rock List Type
Alphabetical List Tree DiagramDetailed Mineral List:
ⓘ 'Biotite' Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Calcite Formula: CaCO3 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Gold Formula: Au References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Hematite Formula: Fe2O3 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Quartz Formula: SiO2 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Quartz var. Chalcedony Formula: SiO2 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Sanidine Formula: K(AlSi3O8) References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ Topaz Formula: Al2(SiO4)(F,OH)2 References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
ⓘ 'Wolframite Group' References: Patrick LahrIdentified by The Marsh Fox: Visual Identification, XRF, ICP-MS |
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
ⓘ | Gold | 1.AA.05 | Au |
Group 4 - Oxides and Hydroxides | |||
ⓘ | Hematite | 4.CB.05 | Fe2O3 |
ⓘ | Quartz var. Chalcedony | 4.DA.05 | SiO2 |
ⓘ | 4.DA.05 | SiO2 | |
ⓘ | 'Wolframite Group' | 4.DB.30 va | |
Group 5 - Nitrates and Carbonates | |||
ⓘ | Calcite | 5.AB.05 | CaCO3 |
Group 9 - Silicates | |||
ⓘ | Topaz | 9.AF.35 | Al2(SiO4)(F,OH)2 |
ⓘ | Sanidine | 9.FA.30 | K(AlSi3O8) |
Unclassified | |||
ⓘ | 'Biotite' | - | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
List of minerals for each chemical element
H | Hydrogen | |
---|---|---|
H | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
H | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
C | Carbon | |
C | ⓘ Calcite | CaCO3 |
O | Oxygen | |
O | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
O | ⓘ Calcite | CaCO3 |
O | ⓘ Quartz var. Chalcedony | SiO2 |
O | ⓘ Hematite | Fe2O3 |
O | ⓘ Quartz | SiO2 |
O | ⓘ Sanidine | K(AlSi3O8) |
O | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
F | Fluorine | |
F | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
F | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
Mg | Magnesium | |
Mg | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
Al | Aluminium | |
Al | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
Al | ⓘ Sanidine | K(AlSi3O8) |
Al | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
Si | Silicon | |
Si | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
Si | ⓘ Quartz var. Chalcedony | SiO2 |
Si | ⓘ Quartz | SiO2 |
Si | ⓘ Sanidine | K(AlSi3O8) |
Si | ⓘ Topaz | Al2(SiO4)(F,OH)2 |
K | Potassium | |
K | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
K | ⓘ Sanidine | K(AlSi3O8) |
Ca | Calcium | |
Ca | ⓘ Calcite | CaCO3 |
Ti | Titanium | |
Ti | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
Fe | Iron | |
Fe | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
Fe | ⓘ Hematite | Fe2O3 |
Au | Gold | |
Au | ⓘ Gold | Au |
Other Regions, Features and Areas containing this locality
North America PlateTectonic Plate
- Basin and Range BasinsBasin
- Mojave DomainDomain
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SK Star Claim #2, Thomas Range, Juab County, Utah, USA