Formula: CaMgSi2O6
Origin of name: From Greek dis - double and opsis - view
Crystal system: Monoclinic
Crystal class: 2/m
Twinning: Common on {100} or {010}, simple or multiple
Unit cell: a = 9.76 Å, b = 8.93 Å, c = 5.26 Å, β = 105.8°
Colour: Colourless, white, gray, pale green to dark greenish black, brown,
Diaphaneity:
Luster: Vitreous, often dull
Habit: Crystals short prismatic; massive, columnar, granular, lamellar
Hardness: 5.5 to 6.5
Specific gravity: 3.22 to 3.38
Cleavage: 3; {110} good, {100} and {010} parting
Tenacity: Brittle
Streak: White or greyish
Synonyms/varieties: Fassite (Fe3+, Al-rich variety), jeffersonite (Mn, Zn, Fe in 1:1:1 ratio variety), salite (Fe-rich variety), violan (Mn-rich, purple colour)
Comments: Series with hedenbergite and with johannsenite
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