General Information:
Chemical Formula:
(Ca,Mn++)Mn++++4O9·3(H2O)
Composition:
(Molecular Weight = 461.59 gm)
Calcium 6.51 % Ca
Manganese 50.58 % Mn
Hydrogen 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
More details...