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KYANITE PHYSICAL PROPERTIES

• Kyanite Chemical composition: Al₂SiO₅
• Class: nesosilicate
• Kyanite Crystal system: triclinic
• Crystal habit: Kyanite crystals commonly occur as tabular prismatic crystals elongated on c, can be folded or wavy, in bladed agregates, rarely terminated.
• Twinning: multiple twinning common on {100}
• Specific gravity: 3.55 - 3.66
• Kyanite Index of refraction: 1.712 - 1.734
• Birefringence: moderate (0.012-0.016)
• Pleochroism: strong: colorless/violet-blue/cobalt blue
• Kyanite Hardness: 4.5 to 5 parallel to crystal length, 7 to 7.5 perpendicular to length
• Color: usually in shades of blue, also white, gray to black, yellow, green or colorless, often with irregular color zoning.
• Kyanite Luster: vitreous to pearly
• Transparency: translucent to transparent
• Kyanite Cleavage: perfect on {100} and distinct on {010}
• Fracture: splintery to fibrous
• Kyanite Streak: white

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KYANITE BACKGROUND INFORMATION

There are three polymorphs of Al₂SiO₅: andalusite, kyanite and sillimanite. Each of these minerals has the same chemical composition but differing crystal structure.

These three minerals form in aluminous metamorphic rocks. The temperature and pressure are what determines which of these polymorphs will crystallize. Knowing the pressure and temperature stability field for each of these three minerals can be of significant value in understanding metamorphic terrains. Under conditions of high temperature regional metamorphism, sillimanite tends to occur from rocks of appropriate composition. Kyanite crystals are typically found in rocks that formed under conditions of high pressure regional metamorphism. Andalusite is indicative of relatively low pressure conditions of formation, often occuring in contact metamorphic deposits.

KYANITE OCCURRENCE INFO AND DIAGNOSTIC FEATURES

Kyanite crystals most often form in high pressure regionally metamorphosed aluminous rocks and in the quartz veins that cut through them, associated with quartz, muscovite, almandine garnet, biotite, staurolite and corundum. It also occurs in some kimberlite pipes and eclogites associated with pyrope garnet and omphacite.

The blue color in metamorphic kyanite is due to trace amounts of Fe⁺² and Ti⁺⁴ impurities substituting for aluminum. The light blue color of kyanites found in kimberlites is due to trace amounts of chromium.

Kyanite is characterized by its blue color, differing hardnesses, perfect cleavage and bladed crystal form.

KYANITE HISTORY AND USES

Kyanite got its name from the Greek word kyanos, which means blue.

Pulverized kyanite crystals are used in the manufacture of spark plugs and other heat resistant ceramics.
Kyanite gemstones of fine color and transparency are rare, and since the relatively low hardness and well developed cleavage make it comparatively easy to damage, its use as a gemstone is generally limited to earrings, brooches and pendants.

The astrological signs of kyanite are Taurus, Libra and Aires.

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KYANITE METAPHYSICAL PROPERTIES

Wearing Kyanite jewelry is said to be very useful in enhancing one's creativity, broadening one's perspective, and in reaching a better understanding with others. Kyanite is also said to bring calm and tranquility, and to facilitate meditation.

Kyanite is said to help clear sinus congestion, and to help in the treatment of muscular disorders.

For more in-depth metaphysical information, see our Metaphysical Books section.

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