Greigite

Formula:  FeFe2S4

Origin of name:   For Joseph Greig, American petrologist

 

Crystal system:  Cubic

Crystal class:  4/m -3 2/m

Twinning:

Unit cell: a = 9.87 Ǻ

 

Colour:  Pink, tarnishes metallic blue

Diaphaneity:

Luster:  Metallic

Habit:   Intergrown octahedra with curved faces, in groups forming balls; cubes; tiny grains

Hardness:  4 to 4.5

Specific gravity:  4.05

Cleavage:  None

Tenacity:

Streak:

 

Synonyms/varieties:  Melnikovite

 

Comments:  Strongly magnetic

 

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