metamorphic
Ruby-bearing rock (likely ruby in zoisite)
Corundum (ruby, Al₂O₃) in a zoisite-rich matrix; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectThe specimen shows purple-red areas with a dark green, granular matrix, consistent with ruby-in-zoisite material. Ruby has Mohs hardness 9, vitreous luster, and trigonal crystals; the matrix minerals are typically softer. Hardness and composition cannot be confirmed visually.
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Physical properties
The specimen shows purple-red areas with a dark green, granular matrix, consistent with ruby-in-zoisite material. Ruby has Mohs hardness 9, vitreous luster, and trigonal crystals; the matrix minerals are typically softer. Hardness and composition cannot be confirmed visually.
Formation & geological history
Ruby forms when aluminum-rich rocks undergo metamorphism; zoisite-bearing ruby deposits are known from metamorphic rocks in Tanzania. The specimen’s age and locality cannot be determined from appearance alone.
Uses & applications
Ruby is used in jewelry and, synthetically, in lasers and other technical applications; ruby-in-zoisite is mainly sold as a decorative or collector specimen.
Geological facts
Ruby is the red variety of corundum, with its color chiefly caused by chromium. Green zoisite with ruby is popularly called anyolite.
Field identification & locations
Look for ruby’s red-to-purplish patches set in green zoisite, often with dark inclusions; confirm with mineralogical testing, since other minerals can look similar. A small rough specimen like this commonly sells for about $5–$30 USD, depending on locality and quality.
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