BLUE KYANITE Crystal Mineral Specimen - One 2-4+ Oz. Blue Kyanite Blade Crystal Mineral Specimen from Brazil by GeoSpecimens. Weight: 2-4 Oz. Size: 2-4" This sale is for one Blue Kyanite specimen pictured or from the same batch pictured from Minas Gerais, Brazil. Some may have a cut base. KYANITE PROPERTIES: - Kyanite, whose name derives from the Greek word kuanos sometimes referred to as "kyanos", meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite has been used as a semiprecious gemstone, which may display cat's eye chatoyancy, though this use is limited by its anisotropism and perfect cleavage. Color varieties include recently discovered orange kyanite from Tanzania. The orange color is due to inclusion of small amounts of manganese (Mn3+) in the structure. Kyanite is one of the index minerals that are used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism. Color - Blue, white, rarely green, gray, yellow, pink, orange, and black, can be zoned. Crystal habit - Columnar; fibrous; bladed. Crystal system - Triclinic. Cleavage - perfect; imperfect with 79° angle between. Fracture - Splintery. Tenacity - Brittle. Hardness - 4.5-5 parallel to one axis; 6.5-7 perpendicular to that axis. Luster - Vitreous to pearly. Streak - White. Diaphaneity - Transparent to translucent. Specific gravity - 3.53 - 3.65 measured; 3.67 calculated. Courtesy of Wikipedia
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