VS
Name
—
NaNa₂(Fe²⁺₄Fe³⁺)Si₈O₂₂(OH)₂
Formula
—
Mineral Species
Entry type
—
Silicates
Chemical class
—
Monoclinic
Crystal system
—
5–6
Mohs hardness
—
3.3–3.5
Specific gravity
—
Deep bluish gray, gray-green
Streak
—
Vitreous
Luster
—
Perfect on {110}, with intersections of 56± and 124±; parting on {010}
Cleavage
—
C2/m
Space group
—
Amphibole
Structural group
—
Arf · Approved
IMA
—
1823
Named in
—
Black, deep green on thin edges; strongly colored in thin section
Typical colors
—
Na · Fe · Si · O · H
Elements
—