Epistolite

Formula:   Na2(Nb,Ti)2(Si2O7)2(O,F)4 . nH2O

Origin of name:   Form Greek for letter

 

Crystal system:   Triclinic

Crystal class:   1

Twinning:

Unit cell: 

 

Colour:  White, yellowish white, gray, light brown

Diaphaneity:  Translucent

Luster:   Pearly

Habit:   Crystals rectangular plates; thin lamellar aggregates

Hardness:   1 to 1.5

Specific gravity:   2.65 to 2.89

Cleavage:   2; {001} perfect, {110} distinct

Tenacity: 

Streak: 

 

Synonyms/varieties:

 

Comments:

 

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