Geology Home Page
Roger Weller, geology instructor
Chemical Group: silicate
Chemical Formula: Al2SiO5
Color: variable, white, gray rose-red, brown
Luster: vitreous to dull
Specific Gravity: 3.15
Cleavage: one direction
Crystal Forms and
Habits: Orthorhombic system
Crystals are commonly prismatic with nearly square cross sections.
Crystals are often rounded.
Cross sections of crystals have carbonaceous inclusions in a cross-patter: variety chiastolite.
Mineral Associations: found in contact metamorphic shales
Uses: Used in the manufacture of spark plugs.
Dalton, Madera County
White Mountain, Mono County
Arrasuai, Minas Gerais
Toxicity: when-swallowed- low when inhaled- high