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Carnotite



Carnotite

General
CategoryMineral
Chemical formulaK2(UO2)2(VO4)2·3H2O
Identification
ColorYellow, Golden yellow, Greenish yellow
Crystal habitcrusts, earthy masses, foliated and granular aggregates.
Crystal systemMonoclinic; 2/m
Cleavageperfect: one direction
Fractureuneven
Mohs Scale hardness2
Lusterpearly to dull or earthy
Refractive indexnα=1.750 - 1.780,
nβ=1.901 - 2.060,
nγ=1.920 - 2.080
Streakyellow
Specific gravity4 - 5
Other Characteristics 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.

Additional recommended knowledge

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; It also occurs incidentally in Grants, New Mexico and Carbon County, Pennsylvania. It is also reported in Zaire; Morocco; Radium Hill, Australia; and Kazakhstan.

The mineral was first described in 1899 by French scientists M. M. C. Freidel and E. Cumenge, who identified it in specimens from Roc Creek in Montrose County, Colorado, United States.[1] It is named for Marie Adolphe Carnot (1839 - 1920), French mining engineer and chemist.

Several related mineral species exist, including: margaritasite ((Cs,K,H3O)2(UO2)(VO4)2·H2O) and tyuyamunite, (Ca(UO2)2(VO4)2·5-8H2O).

See also

References

  1. ^ Robert J. Wright and Donald L. Everhart (1960) Uranium, in Mineral Resources of Colorado First Sequel, State of Colorado Mineral Resources Board, p.330-331.
  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0-471-80580-7
  • Webmineral
  • Univ. of Virginia
  • Mineral Galleries
  • Mindat.org
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carnotite". A list of authors is available in Wikipedia.
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