General Information:
Chemical Formula:(Mn++,Mg,Zn,Fe++)3(Si,As)2O510(OH,Cl)4
Environment:Forms as an alteration product of primary manganese silicates such as rhodonite.
IMA Status:Approved IMA 1963
Locality:Harstig mine, Pajsberg, Varmland, Sweden.
Name Origin:Named from the Greek for "nut" and "felt," in allusion to its brown color and felted structure.
Physical Properties: Cleavage:[001] Good
Color:reddish brown, yellow, greenish brown, or orange brown.
Density:2.87
Habits:Pseudo Hexagonal - Crystals show a hexagonal outline., Platy - Sheet forms (e.g. micas)., Massive - Uniformly indistinguishable crystals forming large masses.
Hardness:3-3.5 - Calcite-Copper Penny
Streak:light brown
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