Eucryptite in normal light.
Eucryptite as seen in ultra violet
light.
CHEMISTRY - LiAlSiO4
CRYSTALLOGRAPHY - Hexagonal
CRYSTAL GROWTH AND HABITS - Crystals of Eucryptite are rare, common forms are {1010}, {1120} amd {0001}. Eucryptite usually forms sugary crystalline aggregates or is massive.
COLOR AND OPTICAL PROPERTIES - Colorless to gray; transparent to translucent; fluoresces a pinkish red.
HARDNESS - 6.5
SPECIFIC GRAVITY - 2.6
LUSTER - Vitreous to sub vitreous
STREAK - White
BREAKABILITY - Cleavage of crystals is along {0001} and {1010}, conchoidal to uneven fracture; brittle.
OCCURRENCE - Eucryptite is found in lithium rich pegmatites.
ASSOCIATED MINERALS - Albite, Quartz, Spodumene, Amblygonite, Lepidolite, Schorl.
MINERAL NAME - From the Greek for "well" and "hidden" in reference to the difficulty in distinguishing it from its intergrowth with Albite.