Formula: [(Na,K)6Cl2][Ca2Cl2]Si6Al6O24
Origin of name: from Latin quad = four as the mineral has four times the unit cell volume of the related mineral species davyne
Crystal system: Hexagonal
Crystal class: 6/m
Twinning: on {10-10} common
Unit cell: a = 25.771, c = 5.371
Colour: Colourless
Diaphaneity: Transparent
Luster: Vitreous
Habit: prismatic crystal to 2 mm, hexagonal outline to 0.5 mm across
Hardness: 5
Specific gravity: 2.335
Cleavage: 2; {0001} perfect, {1120} distinct
Tenacity: Brittle
Streak: White
Synonyms/varieties:
Comments: a feldspathoid
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