Mineral Name
Chemical Formula
(Ca,Na)2-3(Mg,Fe,Al)5Si6(Si,Al)2O22(OH)2
Preview
Color
various shades of dark green to black
Class
Article
Luster
vitreous to dull
Diaphaneity
translucent
Hardness
5-6
Cleavage
2 directions: {110} imperfect at 56 and 124 degrees
Fracture
uneven
Density
3-3.4
Crystal Shape
crystals prismatic, may be columnar or fibrous
Crystal System
Monoclinic
COinS