Uranmicrolite

General Information:
 Chemical Formula:
(U,Ca)2(Ta,Nb)2O6(OH)
 Composition:
(Molecular Weight = 695.81 gm)
Calcium 6.91 % Ca
Uranium 27.37 % U 
Tantalum 46.81 % Ta
Niobium 2.67 % Nb
Hydrogen 0.14 % H 
Oxygen 16.10 % O 
 Empirical Formula:
U0.8Ca1.2Ta1.8Nb0.2O6(OH)
 IMA Status:
Approved IMA
 Locality:
Fazenda Posse, Brejauba district, Municiop de Conceicao de Serro, Minas Gerias, Brazil.
 Name Origin:
Named for uranium and as a member of the microlite group.
Physical Properties:
 Cleavage:
None
 Color:
greenish brown, yellow brown, or black.
 Density:
5.75 - 5.88, Average = 5.81
 Diaphaniety:
Transparent to Opaque
 Habits:
Octahedral Crystals - Occurs as octahedral shaped crystals., ,
 Hardness:
5.5 - Knife Blade
 Luminescence:
Highly Radioactive.
 Luster:
Greasy (Oily)
 Streak:
yellow
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