Zwieselite

Formula: (Fe,Mn)2(PO4)F

Origin of name: locality Rabenstein, Zwiesel, Germany

 

Crystal system: Monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 12.046 Å, b = 6.446 Å, c = 9.888 Å, β = 107.42°

 

Colour: Clove-brown, alters to brownish black to black

Diaphaneity: Translucent

Luster: Vitreous to resinous

Habit: Crystals rough, poorly developed, massive, pseudocubic

Hardness: 5 to 5.5

Specific gravity: 3.93 to 3.97

Cleavage: 3; {001} good, {010} fair, {100} poor

Tenacity: Conchoidal fracture

Streak: White

 

Synonyms/varieties:

 

Comments: series with triplite

 

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