A trapezohedral crystal of Leucite.
CHEMISTRY - KAlSi2O6
CRYSTALLOGRAPHY - Tetragonal (Pseudo Cubic)
CRYSTAL GROWTH AND HABITS - Commonly forms pseudo cubic trapezohedral crystals. It can also be granular.
COLOR AND OPTICAL PROPERTIES - White or gray.
HARDNESS - 5.5 - 6
SPECIFIC GRAVITY - 2.4 - 2.5
LUSTER - Vitreous
STREAK - White
BREAKABILITY - Very poor cleavage on {110}; conchoidal fracture
OCCURRENCE - Found with potassium rich mafic and ultramafic lava flows.
ASSOCIATED MINERALS - Nepheline, Analcime, Natrolite
MINERAL NAME - From the Greek word leucos for white.