gemstone

Tumbled amethyst quartz

Quartz, SiO₂; purple coloration from trace iron and irradiation, with likely milky quartz and iron-stained areas

AI-generated identification · may be incorrect

Hardness 7 Mohs; purple, white, and yellow-brown coloration; vitreous to waxy luster; trigonal crystal structure; no cleavage, with conchoidal fracture; specific gravity about 2.65. The rounded surface indicates human tumbling or polishing.

Identified August 13, 2026More gemstone →

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At a glance

Common name: Tumbled amethyst quartz
Scientific name: Quartz, SiO₂; purple coloration from trace iron and irradiation, with likely milky quartz and iron-stained areas
Category: gemstone
Identified: August 13, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a small common tumbled stone; approximately $10–$30 if unusually vivid, attractive, or sold as a collectible specimen.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins and volcanic cavities, commonly as crystal linings in basaltic geodes. Amethyst deposits range from Precambrian to recent, with major sources in Brazil, Uruguay, Zambia, and Bolivia.

Uses & applications

Used for inexpensive cabochons, beads, ornaments, and specimens; high-quality transparent material is used in jewelry. This small, heavily included tumbled piece generally has modest commercial value.

Geological facts

Purple amethyst is the most valued quartz variety, though heating can turn it yellow-orange, producing citrine. Yellow-brown patches may be iron staining or included goethite rather than a separate gemstone.

Field identification & locations

Identify by its purple quartz color, glassy fracture, hardness, and inability to scratch with a steel blade while scratching ordinary glass. Commonly found in geodes and amethyst-rich volcanic cavities.