Cannizzarite

Formula:  Pb₄Bi₅S₁₁

Origin of name:  For S. Cannizzaro (1826-1910, Italian chemist, University of Rome

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning: Stellate trillings ans as simple V-shapes

Unit cell: a = 4.13 Å, b = 4.09 Å, c = 15.48 Å, β = 98.56°

Colour:  white to silvery gray, tarnishes iridiscent

Diaphanetiy: Opaque

Luster:  Metallic

Habit:  Tiny acicular crystals < 0.5 mm and aggregates

Hardness:  3

Specific gravity:  6.7

Cleavage:  None

Tenacity: Somewhat malleable

Streak:

Synonyms/varieties:

Comments: Associated with deep fumarolic activity, in sulfide veinlets in greisen Sn-W deposits in granite