Leucite - Encyclopedia

    Class : Silicates
    Subclass : Tectosilicates
    Crystal system : Tetragonal
    Chemistry : KAlSi₂O₆
    Rarity : Uncommon

Leucite is an accessory feldspathoid, characteristic of alkaline volcanic rocks rich in potassium and deficient in silica (tephrites), sometimes also present in potassium basalts, basanites and phonolites. Its name comes from the Greek leucos (white) in reference to its color. The crystalline form is constant and characteristic : we almost always observe well-formed trapezoidal crystals, more precisely tetragonotrioactahedra (or leucitohedra), consisting in fact of twinned tetragonal crystals ; the striation of the faces betraying the organization into polysynthetic twins of the mineral. Leucite is sometimes also grainy or massive. Translucent, rarely transparent, it is colorless, greyish, whitish or yellowish. It easily deteriorates in meteoritic conditions, becoming opacified and releasing potassium salts, resulting in the exceptional fertility of the soils derived from it.

Twins are common and polysynthetic on {001} and {110}.

No fake inventories for this mineral species.