mineral

Tumbled quartz-rich stone, possibly amethyst/agate

Quartz (SiO₂), potentially iron-stained or amethyst-bearing chalcedony

AI-generated identification · may be incorrect

Small polished/tumbled pebble with purple-blue and brown coloration, vitreous to waxy luster, and no visible cleavage; quartz hardness is Mohs 7 and specific gravity about 2.65. The brown area likely reflects iron oxides or included matrix.

Identified August 26, 2026More mineral →

Explore Tumbled quartz-rich stone, possibly amethyst/agate in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Likely formed in silica-rich volcanic cavities or hydrothermal veins, where quartz or chalcedony crystallized and later acquired iron staining; the specimen has been mechanically tumbled and polished. Exact geological age cannot be determined visually.

Uses & applications

Used mainly as a decorative, lapidary, or collectible stone; quartz varieties are also used in glass, ceramics, abrasives, and electronics. Its small size and modest color zoning make it more ornamental than gem-grade.

Geological facts

The purple color may result from trace iron and irradiation in amethyst, but the image is insufficient to confirm true amethyst. Strongly colored specimens may fade with prolonged heating or sunlight.

Field identification & locations

Common sources include Brazil, Uruguay, Madagascar, India, and the United States. Field identification requires a scratch test against glass, inspection for quartz-like translucency, and ideally refractive-index or chemical testing.