VS
Name
—
Na₂(Fe²⁺₃Fe³⁺₂)Si₈O₂₂(OH)₂
Formula
—
Mineral Species
Entry type
—
Silicates
Chemical class
—
Monoclinic
Crystal system
—
5–6
Mohs hardness
—
3.28–3.44
Specific gravity
—
bluish-gray
Streak
—
Vitreous to silky
Luster
—
Perfect on {110}, intersecting at 56± and 124 ±; partings on {100}, {010}
Cleavage
—
—
Space group
—
Amphibole
Structural group
—
Rbk · Approved
IMA
—
1888
Named in
—
Blue, Black
Typical colors
—
Na · Fe · Si · O · H
Elements
—