Vishnevite

Formula: (Na,K,Ca)₈(Si₆Al₆)O₂₄(SO₄).2H₂O

Origin of name: after locality Vishnevye Gory, Urals, Russia

Crystal system: hexagonal

Crystal class: 6

Twinning:

Unit cell: 

Colour: colourless, white, yellow, orange, pink to reddish, pale blue to pale gray

Diaphaneity: transparent to translucent

Luster: vitreous, pearly or greasy

Habit: crystals prismatic, rare, massive

Hardness: 5 to 6

Specific gravity: 2.32 to 2.42

Cleavage: 2; {10-10} perfect, {0001} poor

Tenacity: 

Streak: colourless

Synonyms/varieties:

Comments: series with cancrinite