Ferrosilite

Formula:  (Fe,Mg)₂Si₂O₆

Origin of name:   From composition

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning:   On {100}

Unit cell: a = 18.43 Ǻ, b = 9.080 Ǻ, c = 5.238 Ǻ

Colour:  Dark green

Diaphaneity:

Luster:

Habit:

Hardness:  5 to 6

Specific gravity:  3.96

Cleavage:  4; {210} and {2-10} good, {100} and {010} partings

Tenacity: 

Streak: 

Synonyms/varieties:  Orhoferrosilite, hypersthene

Comments:   Series with enstatite; dimorphous with clinoferrosilite