Wöhlerite

Formula: NaCa2(Zr,Nb)Si2O7(O,OH,F)2

Origin of name: Named for Friedrich Wohler (1800-1882), German chemist, Gottingen, Germay.

 

Crystal system: monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 10.8, b = 10.26, c = 7.26, β = 108.95°

 

Colour: Light yellow to dark yellow, gray, brown

Diaphaneity: Transparent to translucent

Luster: Vitreous to greasy or dull

Habit: Crystals prismatic or tabular, irregular grains to 3 cm, twinned

Hardness: 5.5 to 6

Specific gravity: 3.41 to 3.44

Cleavage: 3; {010} distinct, {100} and {110} indistinct

Tenacity: Brittle

Streak: Yellowish-white, pale yellow

 

Synonyms/varieties:

 

Comments: 

 

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