Sphalerite

Formula: (Zn,Fe)S

Origin of name: from Greek for treacherous

 

Crystal system: cubic

Crystal class: -43m

Twinning: common on {111} simple, penetration or lamellar

Unit cell: a = 5.406 Å

 

Colour: brown, black, yellow, green, red, gray, white, colourless

Diaphaneity: 

Luster: resinous to adamantine

Habit: crystals tetrahedral, may appear octahedral, sometimes dodecahedral, massive, cleavable, granular, stalactitic

Hardness: 3.5 to 4

Specific gravity: 3.9 to 4.1

Cleavage: 1; {011} perfect

Tenacity: conchoidal, brittle

Streak: colourless to pale brown

 

Synonyms/varieties: blackjack, blende, cleiophane (pale-coloured variety), marasmolite, marmatite (Fe-rich variety), zincblende

 

Comments: trimorphous with matraite and wurtzite, also from a meteorite

 

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