General Information:
Chemical Formula:
(Co,Mg)(H3O)2[(UO2)SiO4]2·3(H2O)
Composition:
(Molecular Weight = 835.75 gm)
Magnesium 0.29 % Mg
Uranium 56.96 % U
Cobalt 6.35 % Co
Silicon 6.72 % Si
Hydrogen 0.96 % H
Oxygen 28.72 % O
Empirical Formula:
Co0.9Mg0.1(H3O)2(UO2)2(SiO4)2·(H2O)
Environment:
In the oxidation zones of uranium ores.
IMA Status:
Approved IMA 1982
Locality:
Shikolobwe, Shava, Zaire.
Name Origin:
Named from the French "oursin", sea urchin, in allusion to the radiating habit of the acicular crystals.
Physical Properties:
Cleavage:
[???] Good
Color:
pale yellow.
Density:
3.674
Diaphaniety:
Transparent to Translucent
Habits:
Acicular - Occurs as needle-like crystals., Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Aggregates - Made of numerous individual crystals or clusters.
Hardness:
3-3.5 - Calcite-Copper Penny
Luster:
Vitreous (Glassy)
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