Eucriptite

Key facts

Mineral.name

Eucryptite

Mineral.category

Silicate mineral

Mineral.image

Eucryptite-202043.jpg

Mineral.caption

Eucryptite grains in albite from the type locality (size: 9.3 × 7.0 × 2.8 cm)

Mineral.formula

LiAlSiO4

Mineral.IMAsymbol

Ecp

Mineral.system

Trigonal

Mineral.class

Rhombohedral () H-M symbol: ()

Mineral.symmetry

R

Mineral.unit cell

a = 13.48, c = 9.01 [Å]; Z = 18

Mineral.color

Brown, colorless, white

Mineral.habit

Rare as euhedral crystals, coarse crystalline aggregates and massive

Mineral.cleavage

Indistinct on {100} and {0001}

Mineral.fracture

Conchoidal

Mineral.tenacity

Very brittle

Mineral.mohs

6.5

Mineral.luster

Vitreous

Mineral.refractive

nω = 1.570 – 1.573 nε = 1.583 – 1.587

via Wikipedia infobox