mineral
Amethyst (rough crystal)
Quartz, SiO₂; purple coloration from trace iron and natural irradiation
AI-generated identification · may be incorrectMohs hardness 7; translucent purple with vitreous luster and conchoidal fracture; trigonal crystal structure. The small specimen appears to be a rough crystal point, though its faces are not clearly visible.
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Physical properties
Mohs hardness 7; translucent purple with vitreous luster and conchoidal fracture; trigonal crystal structure. The small specimen appears to be a rough crystal point, though its faces are not clearly visible.
Formation & geological history
Forms in silica-rich hydrothermal fluids, commonly lining cavities in volcanic rocks; deposits range from geologically recent to hundreds of millions of years old.
Uses & applications
Used for jewelry, carvings, and mineral collecting; larger crystals are also decorative stones.
Geological facts
Amethyst is the purple variety of quartz, and its color can fade with prolonged heat or sunlight.
Field identification & locations
Identify by its purple color, glassy luster, and hardness sufficient to scratch glass; common sources include Brazil, Uruguay, and Zambia.
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