VS
Name
—
(K,Ca,Na)(Fe,Mg,Al)₈(Si,Al)₁₂(O,OH)₃₆·nH₂O
Formula
—
Mineral Species
Entry type
—
Silicates
Chemical class
—
Triclinic
Crystal system
—
3–4
Mohs hardness
—
2.59–2.96
Specific gravity
—
—
Streak
—
Pearly to vitreous on cleavage surface, may be submetallic
Luster
—
Perfect on {001}, imperfect on {010}
Cleavage
—
P-1
Space group
—
Stilpnomelane, Clay
Structural group
—
Stp · Approved
IMA
—
1827
Named in
—
Black, greenish black, yellowish bronze, greenish bronze; in thin section, golden brown, dark brown, green
Typical colors
—
K · Ca · Na · Fe · Mg · Al · Si · O · H
Elements
—