VS
Name
—
(Fe²⁺,Fe³⁺)₃(Si,Fe³⁺)₂O₅(OH)₄
Formula
—
Mineral Species
Entry type
—
Silicates
Chemical class
—
Hexagonal
Crystal system
—
3.5
Mohs hardness
—
3.34–3.35
Specific gravity
—
Dark olive-green
Streak
—
Brilliant
Luster
—
Perfect on {001}
Cleavage
—
R3
Space group
—
Serpentine, Clay
Structural group
—
Cro · Grandfathered
IMA
—
1821
Named in
—
Coal-black to brownish black; thin laminae emerald-green by transmitted light, brown to yellow-brown on edges
Typical colors
—
Fe · Si · O · H
Elements
—