Radtkeite

Formula: Hg₃S₂Cl₁₁

Origin of name: for Arthur S. Radtke, American geologist

Crystal system: orthorhombic

Crystal class: 222 or mm2 or 2/m 2/m 2/m

Twinning:

Unit cell: 

Colour: yellow-orange

Diaphaneity: opaque, translucent when thin

Luster: adamantine

Habit: as 2 micron grains and dispersed grains, coatings and prismatic crystals to 30 micron

Hardness: 2 to 3

Specific gravity: 7.0

Cleavage: 3; {010} perfect, {001}, {100} very good

Tenacity: 

Streak: yellow-orange

Synonyms/varieties:

Comments: in sunlight darkens in minutes to black