Vrbaite

Formula: Tl₄Hg₃Sb₂As₈S₂₀

Origin of name: for Karl Vrba, Czech mineralogist

Crystal system: orthorhombic

Crystal class: mm2

Twinning:

Unit cell: 

Colour: dark grayish black, with bluish tinge, thin fragments dark red

Diaphaneity: translucent in thin fragments

Luster: submetallic to metallic

Habit: crystals thick tabular or pyramidal, small

Hardness: 3.5

Specific gravity: 5.3

Cleavage: 1; {010} good

Tenacity: 

Streak: pale yellowish red

Synonyms/varieties:

Comments: