Blue Kyanite in Muscovite Matrix
Kyanite var. Disthene with Muscovite Mica · Mineral Specimen and Semi-Precious Gemstone
Crystal System
Triclinic (Kyanite) and Monoclinic (Muscovite); Twinning is common on {100}, typically found in bladed, elongated, or tabular habits.
Mineral Group
Silicates; Subgroup: Nesosilicate (Kyanite) and Phyllosilicate (Muscovite)
Chemical Formula
Al2SiO5 (Kyanite) with KAl2(AlSi3O10)(OH)2 (Muscovite)
Formation Process
Metamorphic formation, occurring under high-pressure regional metamorphism of clay-rich sedimentary rocks (pelites). Kyanite is an index mineral for high-pressure environments.
About This Crystal
The specimen features translucent to transparent bladed blue kyanite crystals embedded within a silvery-white, pearly, foliated muscovite mica matrix. The kyanite exhibits a vitreous luster and distinct color zoning, while the mica shows a characteristic metallic-pearly sheen and flaky structure.
Physical Characteristics
Color: Sky blue to deep blue kyanite, silvery-white mica; Streak: White; Cleavage: Perfect {100} and good {010} for kyanite, perfect basal for mica; Specific Gravity: 3.53–3.67; Fluorescence: Weak red under UV light in some specimens.
Optical Properties
Biaxial negative; Refractive Index: 1.712–1.735; Birefringence: 0.012–0.020; Pleochroism: Strongly pleochroic (colorless to violet-blue to cobalt blue).
Hardness & Durability
Origin Region
Notable sources include Brazil (Minas Gerais), Nepal, India, and the United States (North Carolina). Typically forms in metamorphic rocks like schists and gneisses.
Hardness & Durability
Highly anisotropic hardness for Kyanite: Mohs 4.5–5.0 parallel to the length of the crystal and 6.5–7.0 perpendicular to it. Muscovite is Mohs 2.0–2.5. Brittle tenacity.
Care & Maintenance
Avoid ultrasonic and steam cleaning due to cleavage planes. Clean with lukewarm soapy water and a soft brush. Store separately to prevent the soft mica from being scratched or the kyanite from splintering.
Rarity & Value
Common mineral but high-quality large blue blades in matrix are sought after by collectors. Value is determined by color intensity, crystal size, and lack of damage to the blades. Generally affordable but rare in gem quality.
Special Characteristics
Kyanite is one of the few minerals that exhibits a dramatic difference in hardness depending on the direction of testing (anisotropy). It also features prominent bladed crystal habits and sharp color zoning.
Lore & History
Historically used in industrial ceramics and spark plugs due to its heat resistance. In metaphysical lore, it is believed to be a stone of alignment that does not retain negative energy and is associated with the Throat and Third Eye chakras.