Carnotite
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| Carnotite | |
|---|---|
| General | |
| Category | Mineral |
| Chemical formula (or Composition) | K2(UO2)2(VO4)2·3H2O |
| Identification | |
| Color | Yellow, Golden yellow, Greenish yellow |
| Crystal habit | crusts, earthy masses, foliated and granular aggregates. |
| Crystal system | Monoclinic; 2/m |
| Cleavage | perfect: one direction |
| Fracture | uneven |
| Mohs Scale hardness | 2 |
| Luster | pearly to dull or earthy |
| Refractive index | nα=1.750 - 1.780 nβ=1.901 - 2.060 nγ=1.920 - 2.080 |
| Pleochroism | . |
| Streak | yellow |
| Specific gravity | 4 - 5 |
| Other | Radioactive - not fluorescent |
Carnotite is a potassium uranium vanadate mineral with chemical formula: K2(UO2)2(VO4)2·3H2O. The water content can vary and small amounts of calcium, barium, magnesium, iron, and sodium are often present.
Carnotite is a bright to greenish yellow mineral that occurs typically as crusts and flakes in sandstones. Amounts as low as one percent will color the sandstone a bright yellow. The high uranium content makes carnotite an important uranium ore and also radioactive. It is a secondary vanadium and uranium mineral usually found in sedimentary rocks in arid climates. It is an important ore of uranium in the Colorado Plateau region of the United States where it occurs as disseminations in sandstone and concentrations around petrified logs. Occurs in the states of Wyoming, Colorado, Arizona, Utah, Grants, New Mexico, and also in Carbon County, Pennsylvania. It is also reported in Zaire; Morocco; Radium Hill, Australia; and Kazakhstan.
It is named for Marie Adolphe Carnot (1839 - 1920), French mining engineer and chemist.
Several related mineral varieties exist, including: margaritasite ((Cs,K,H3O)2(UO2)(VO4)2·H2O) and tyuyamunite, (Ca(UO2)2(VO4)2·5-8H2O).
References
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0471805807
- Webmineral (http://webmineral.com/data/Carnotite.shtml)
- Univ. of Virginia (http://www.evsc.virginia.edu/tours/rockmin/carnotite.shtml)
- Mineral Galleries (http://mineral.galleries.com/minerals/phosphat/carnotit/carnotit.htm)
- Mindat.org (http://www.mindat.org/min-907.html)