Blue Kyanite in Quartz

Physical Properties

Hardness: Dual hardness (4.5-5 parallel to axes, 6.5-7 across axes); Color: Blue with white streaks; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Perfect {100}; Specific gravity: 3.53–3.67

Formation & Geological History

Formed during regional metamorphism of clay-rich sedimentary rocks at high pressure. Typically found in mica schists, gneisses, and associated pegmatite veins.

Uses & Applications

Used in the manufacture of refractory products like bricks and mortars for high-heat furnaces; also used in porcelain, jewelry, and as a popular metaphysical/collecting specimen.

Geological Facts

Kyanite is an aluminosilicate polymorph, sharing the same chemistry as Andalusite and Sillimanite but forming under different temperature and pressure conditions. Its name is derived from the Greek word 'kyanos', meaning deep blue.

Field Identification & Locations

Identify in the field by its distinct bladed crystal habit, blue color, and anisotropic hardness (much softer lengthwise than widthwise). Commonly found in Brazil, Nepal, and the USA (North Carolina).

Identified on: 4/14/2026

Mode: Standard