ellisite

Formula: TI3AsS3

Environment:

In a hydrothermal gold deposit, in mineralized, argillaceous, carbonaceous dolomite beds

Physical Properties:

1011 Perfect Cleavage!
Dark Grey
Density of 7.1
Opaque
Jagged, torn surface (Hackly)- like fractured metal
Rhombohedral crystals
Hardness of 2
Metallic luster
Pale brown streak

http://webmineral.com/data/Ellisite.shtml