Clarkeite
A variety of Minerals
What is Clarkeite?
Clarkeite is a uranium oxide mineral of with the chemical formula(Na,Ca,Pb)2(UO2)2(O,OH)3 or (Na,Ca,Pb)(UO2)O(OH)•0-1H2O. Its color varies from dark brown to reddish orange. Clarkeite forms by oxidation and replacement of uraninite late during pegmatite crystallization. Although uraninite-bearing granite pegmatites are common, clarkeite is rare and occurs intimately intergrown with other uranium minerals. It is known from only two localities; the Spruce Pine pegmatite district in western North Carolina, US, and Rajputana, in the Ajmer district, India. Clarkeite is the only known naturally occurring high-temperature uranate. The general formula for ideal clarkeite is Na(UO2)O(OH)0–1. It was named for Frank Wigglesworth Clarke (1847–1931), American mineral chemist, and former chief chemist of the United States Geological Survey.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Clarkeite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Clarkeite Localities Map
See where Clarkeite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- Dark red-brown, dark brown
- Hardness (Mohs)
- 4 - 4.5
- Density
- 6.39 g/cm³
- Streak
- Yellow-brown
Chemical Properties
- Chemical Formula
- (Na,Ca,Pb)(UO2)O(OH) · 0-1H2O
- Elements
- H, Na, O, U
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Clarkeite FAQs
How do I identify Clarkeite?
Clarkeite can be identified by its hardness of 4 - 4.5 on the Mohs scale, Dark red-brown color. Look for these key characteristics when examining specimens.
What color is Clarkeite?
Clarkeite typically appears in Dark red-brown, dark brown. Color can vary depending on impurities and formation conditions.
How hard is Clarkeite?
Clarkeite has a hardness of 4 - 4.5 on the Mohs scale. This gives it moderate hardness.
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