
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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