General Information:
Chemical Formula:(Ca,Mn++)Mn++++4O9·3(H2O)
Composition:(Molecular Weight = 461.59 gm)Calcium 6.51 %
CaManganese 50.58 %
MnHydrogen 1.31 %
H Oxygen 41.59 %
O Empirical Formula: Ca0.75Mn2+0.25Mn4+4O9·3(H2O)
Environment:In cavities in limonite.
Locality:Rancie, near Vicdessos, Ariege, France.
Name Origin:Named for the locality.
Physical Properties: Cleavage:None
Color:violet brown, black, or silver gray.
Density:3 - 3.2, Average = 3.1
Diaphaniety:Transparent to Opaque
Habits:Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Lamellar - Thin laminae producing a lamellar structure., Stalactitic - Shaped like pendant col umns as stalactites or stalagmites (e.g.
Hardness:2.5-3 - Finger Nail-Calcite
Luster:Metallic - Dull
Streak:dark brown
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