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Roger Weller, geology instructor
Chemical Group: silicate
Chemical Formula: Ca6[Al(OH,F)]Al2(SiO4)5
Color: brown to green Streak: white
Transparency: subtransparent to subtranslucent
Specific Gravity: 3.35 to 3.45
Luster: vitreous to resinous Fracture: sub-conchoidal to uneven
Cleavage: not very distinct
Crystals are prismatic or pyramidal.
May also occur in massive form.
Mineral Associations: grossularite, phlogopite, diopside, wollastonite, epidote
Identifying Characteristics: 4 sided prismatic crystals and associated with garnet
Toxicity: when-swallowed- when inhaled-
Additional Information: Also known as idocrase (when massive, resembles jade)