metamorphic
Ruby in Kyanite
Al2O3 (Corundum) in Al2SiO5 (Kyanite-Fuchsite-Quartz)
Hardness: 6-7 (Kyanite/Quartz matrix) with 9 (Ruby inclusions); Color: Blue, green, and silver-gray matrix with red/pink hexagonal inclusions; Luster: Vitreous to pearly; Crystal structure: Triclinic (Kyanite) and Trigonal (Ruby).
- Hardness
- 6-7 (Kyanite/Quartz matrix) with 9 (Ruby inclusions)
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-7 (Kyanite/Quartz matrix) with 9 (Ruby inclusions); Color: Blue, green, and silver-gray matrix with red/pink hexagonal inclusions; Luster: Vitreous to pearly; Crystal structure: Triclinic (Kyanite) and Trigonal (Ruby).
Formation & geological history
Formed under high-pressure regional metamorphism of clay-rich sedimentary rocks (pelites). The rubies grow as porphyroblasts within the kyanite-rich matrix during the metamorphic process.
Uses & applications
Primarily used as a lapidary material for cabochons, beads, and decorative carvings. Highly valued by mineral collectors for its contrasting colors and by the metaphysical community.
Geological facts
A unique feature of this rock is that under short-wave UV light, the ruby inclusions will often glow a bright hot pink or red, while the kyanite remains inert. It is often found associated with green Fuchsite.
Field identification & locations
Identify in the field by the high specific gravity, the distinct bladed habit of kyanite crystals, and the presence of deep red hexagonal corundum (ruby) spots. Most common specimens originate from India or Russia.
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