Berndtite

Formula:  SnS₂

Origin of name:  For Fritz Berndt, German geologist, Corporatión Minera de Bolivia, Oruro, Bolivia

Crystal system:  Hexagonal

Crystal class:  -2T -3 2/m; -4H 6mm

Twinning:

Unit cell: -2T a = 3.647 Å, b = 3.647 Å, c = 5.899 Å 90 90 120 ; -4H 3.647 3.647 11.811 90 90 120

Colour:  Pale yellow

Diaphaneity:  Translucent to transparent

Luster:  Resinous

Habit:  Tabular hexagonal

Hardness:  1

Specific gravity:  4.5

Cleavage:

Tenacity:

Streak:  Golden yellow

Synonyms/varieties:

Comments:  Data are given for berndtite-2T and -4T polytypes. Found as a secondary mineral in tin sulfide ores, also in high-temperature deposits that are hydrothermally altered