VS
Name
—
(Na,Ca,K,Ba,Sr)₁₋ₓ(Mn,Mg,Al)₆O₁₂·3-4H₂O
Formula
—
Mineral Species
Entry type
—
Oxides & Hydroxides
Chemical class
—
Monoclinic
Crystal system
—
1.33
Mohs hardness
—
3.66
Specific gravity
—
Black
Streak
—
Metallic to dull; silky in aggregates
Luster
—
{100} and {010}, perfect
Cleavage
—
P2/m
Space group
—
—
Structural group
—
Tdr · Approved
IMA
—
1934
Named in
—
Black to dark brownish black; in transmitted light, brown; in reflected light, gray-white
Typical colors
—
Na · Ca · K · Ba · Sr · Mn · Mg · Al · O · H
Elements
—