Color is typically blue, violet, gray, brownish or colorless. Luster is vitreous. Transparency crystals are transparent to translucent. Crystal Habits include rare prismatic crystals but is usually massive, or in compact grains embedded in metamorphic schists and gneisses. Also found as pebbles and grains in alluvial deposits.
Cleavage is poor in one direction.
Fracture is subconchoidal. Streak is white. Associated Minerals are almandine , corundum , andalusite , biotite and feldspars . Best Field Indicators are hardness, lack of good cleavage, density, color and pleochroism.