Dorrite

Formula:   Ca₂Mg₂Fe₄Al₄Si₂O₂₀

Origin of name:   For John Dorr Jr., American geologist

Crystal system:   Triclinic

Crystal class:   1 or -1

Twinning:

Unit cell: 

Colour:   Dark red-brown

Diaphaneity:  Opaque

Luster:   Submetallic

Habit:   Anhedral to prismatic grains to 0.1 mm

Hardness:   5

Specific gravity:   3.9

Cleavage:   2; {010}, {001}

Tenacity: 

Streak:   Gray

Synonyms/varieties:

Comments: