Radioactive mineral
Carnotite Carnotite in fossilized wood from St. George, Utah
Category Vanadate mineral Formula (repeating unit) K2 (UO2 )2 4 )2 · 3H2 O IMA symbol Cnt[1] Strunz classification 4.HB.05 Crystal system Monoclinic Crystal class Prismatic (2/m) (same H-M symbol ) Space group P2 1 /aUnit cell a = 10.47 Å , b = 8.41 Å, c = 6.91 Å; β = 103.83°; Z = 2 Color Bright yellow to lemon-yellow, may be greenish yellow. Crystal habit Crusts, earthy masses, foliated and granular aggregates. Twinning On {001} as both twin and composition plane Cleavage Perfect on {001}, micaceous Fracture uneven Mohs scale hardness 2 Luster Dull, earthy; silky when crystalline Streak yellow Diaphaneity Semitransparent Specific gravity 4.70 Optical properties Biaxial (−) Refractive index nα =1.750 – 1.780, nβ =1.901 – 2.060, nγ =1.920 – 2.080 Birefringence δ = 0.200 2V angle Measured: 43° to 60°, Calculated: 26° to 36° Other characteristics Radioactive , not fluorescentReferences [2] [3] [4] [5] [6]
Carnotite is a potassium uranium vanadate radioactive mineral with chemical formula K 2 (U O 2 )2 (V O4 )2 · 3H2 O . The water content can vary and small amounts of calcium , barium , magnesium , iron , and sodium are often present.
Occurrence
Carnotite from the Happy Jack Mine, Utah Carnotite is a bright 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 . It is a secondary vanadium and uranium mineral usually found in sedimentary rocks in arid climates.
In the United States it is an important ore of uranium in the Colorado Plateau region of the United States where it occurs as disseminations in sandstone [3] petrified logs. It also occurs in the U.S. states of Wyoming , Colorado , South Dakota , Nevada , Arizona , and Utah . It also occurs incidentally in Grants, New Mexico , and Carbon County, Pennsylvania .[7]
Carnotite is reported in Congo (Kinshasa) , Morocco , Australia (Radium Hill ) and Kazakhstan .[7] Pakistan carnotite occurs in the Upper Miocene middle Siwaliks sandstone (Dhokpathan Formation), in the vicinity of Takhat Nasrati, Karak District .[citation needed
Name and discovery
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.[8] Marie Adolphe Carnot (1839–1920), French mining engineer and chemist .[5]
Uses
Carnotite is an ore of uranium. At times in the early 20th century, it was mined primarily for radium or vanadium.
The mineral was used to produce quack devices involving radioactive substances .
Radioactive, not fluorescent
