Melanotekite

Formula:  Pb₂Fe₂Si₂O₉

Origin of name:  From Greek for black and to melt

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning: 

Unit cell: 

Colour:  Black to blackish gray

Diaphaneity:  Nearly opaque

Luster:  Metallic to greasy

Habit:  Crystals prismatic; massive, cleavable

Hardness:  6.5

Specific gravity:  5.7 to 6.19

Cleavage:  2

Tenacity: 

Streak:  Greenish gray

Synonyms/varieties:

Comments:  Series with kentrolite