Eudidymite

Formula:   NaBeSi3O7(OH)

Origin of name:   From Greek for good and twin

 

Crystal system:   Monoclinic

Crystal class:   2/m

Twinning:

Unit cell: 

 

Colour:  White or colourless, gray, yellow, blue, violet

Diaphaneity:  Transparent to translucent

Luster:   Vitreous, pearly on cleavage

Habit:   Crystals tabular; coarsely crystalline; finely crystalline to cryptocrystalline; spherulitic

Hardness:   6 to 7

Specific gravity:   2.55

Cleavage:   2; {001} perfect, {100} distinct

Tenacity: 

Streak: 

 

Synonyms/varieties:

 

Comments:   Dimorphous with epididymite

 

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