Norrishite

Formula: KLiMn₂Si₄O₁₂

Origin of name: for Keith Norris, Australian scientist

Crystal system: monoclinic

Crystal class: 2/m

Twinning: 

Unit cell: 

Colour: black, green, yellow

Diaphaneity: 

Luster: vitreous

Habit: flakes to 1.5 mm across

Hardness: 2.5

Specific gravity: 3.264

Cleavage: 3; {001} perfect, {100} and {010} weak

Tenacity: 

Streak: 

Synonyms/varieties:

Comments: shiny black crystals, some have green core and yellow rim