Asbolane

Formula: (Co, Ni)_1-y(MnO₂)_2-x(OH)_2-2y+2x^.nH₂O

Origin of name:  From Greek asbole - soot

Crystal system:  Hexagonal

Crystal class:  Unknown

Twinning:

Unit cell: a = 2.832 Å, c = 9.34 Å or a = 3.04 Å, c = 9.34 Å

Colour:  Black to brownish black

Diaphaneity: Opaque

Luster: Earthy, dull

Habit:  Submicron to several microns wide platelets, massive

Hardness: 6

Specific gravity: 

Cleavage: 

Tenacity:

Streak: Black

Synonyms/varieties: Cobaltian wad

Comments:  In formula, x & y <1. Found as a weathering product in silicic rocks; in siliceous schists; widespread in residual soils above ultramafic rocks.