metamorphic
Blue-gray metamorphic rock, likely gneiss or schist
Quartz–feldspar–mica assemblage; exact identification requires testing
AI-generated identification · may be incorrectHardness about 6–7 overall; blue-gray, white, and tan coloration with a coarse, sparkly texture and possible foliation. Likely vitreous quartz, feldspar, and mica; cleavage occurs in mica and feldspar, not quartz.
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Physical properties
Hardness about 6–7 overall; blue-gray, white, and tan coloration with a coarse, sparkly texture and possible foliation. Likely vitreous quartz, feldspar, and mica; cleavage occurs in mica and feldspar, not quartz.
Formation & geological history
Formed when pre-existing rock underwent elevated temperature and pressure, producing recrystallization and mineral alignment. Its precise geological age and locality cannot be determined from the image.
Uses & applications
Used mainly as a decorative or collection specimen; similar gneisses and schists can serve as building stone, aggregate, or landscaping material.
Geological facts
The purple-blue appearance may reflect quartz, feldspar, or minor blue minerals, but it is not diagnostic of a specific gemstone. A streak, hardness, and acid test would substantially improve identification.
Field identification & locations
Look for planar foliation, visible mica flakes, interlocking grains, and resistance to scratching by steel. Common in ancient continental mountain belts worldwide; estimated value is $2–$20 for a hand-sized common specimen, higher if confirmed as unusual material.
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