mineral
Polished amethyst-bearing rock, likely amethyst in matrix
Amethyst (purple quartz, SiO₂), with an unidentified dark host-rock matrix
AI-generated identification · may be incorrectPurple, vitreous quartz contrasts with a dark, mottled matrix; quartz has Mohs hardness 7, trigonal crystal structure, and no cleavage. The specimen is polished, so natural crystal faces are not visible.
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Physical properties
Purple, vitreous quartz contrasts with a dark, mottled matrix; quartz has Mohs hardness 7, trigonal crystal structure, and no cleavage. The specimen is polished, so natural crystal faces are not visible.
Formation & geological history
Amethyst forms when iron-bearing quartz crystallizes in silica-rich fluids, commonly in volcanic cavities; the matrix may be volcanic rock. Age cannot be determined from the image.
Uses & applications
Primarily a decorative or collectible specimen; amethyst is also used in jewelry and ornamental objects.
Geological facts
Amethyst’s purple color is associated with trace iron and natural irradiation; heating can alter its color.
Field identification & locations
Look for purple quartz with glassy luster and hardness sufficient to scratch glass; common sources include Brazil, Uruguay, and Zambia. The specific matrix is not identifiable from this view.
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