mineral
Tumbled amethyst (tentative)
Amethyst, purple variety of quartz (SiO₂)
AI-generated identification · may be incorrectSmall polished crystal with purple and gray coloration, vitreous luster, and likely translucent edges; Mohs hardness 7, trigonal crystal structure, no cleavage, and specific gravity about 2.65.
Identified More mineral →
Explore Tumbled amethyst (tentative) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Small polished crystal with purple and gray coloration, vitreous luster, and likely translucent edges; Mohs hardness 7, trigonal crystal structure, no cleavage, and specific gravity about 2.65.
Formation & geological history
Forms when iron-bearing quartz crystallizes in gas cavities of volcanic rocks, especially basalt, with irradiation producing the purple color. Most commercial material formed in Mesozoic–Cenozoic volcanic settings, though the exact age is unknown.
Uses & applications
Used for cabochons, beads, carvings, ornamental objects, and mineral collecting; small tumbled pieces have modest value.
Geological facts
The purple color ranges from pale lilac to deep violet and may fade with prolonged sunlight or heating. Image-based identification is not definitive because purple fluorite or dyed quartz can look similar.
Field identification & locations
Common sources include Brazil, Uruguay, Zambia, and Mexico. Confirm with hardness testing (scratches glass, but not corundum), lack of cleavage, and quartz-like fracture; avoid destructive tests on a polished specimen.
