mineral

Likely polished/tumbled quartz-rich specimen

Quartz, silicon dioxide (SiO₂), possibly an agate or chalcedony variety

AI-generated identification · may be incorrect

Appears translucent gray-brown with a purple-pink zone and glassy to waxy luster; likely hardness 6.5–7, trigonal crystal structure, no cleavage, and conchoidal fracture. Exact identification is limited by the plastic case, reflections, and image quality.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Quartz and chalcedony form from silica-rich fluids filling cavities or fractures, commonly in volcanic rocks; formation may range from Paleozoic to recent depending on locality. Purple coloration can result from iron-related defects, as in amethyst.

Uses & applications

Used for jewelry, lapidary pieces, ornaments, and mineral collecting; agate and quartz are also used industrially as abrasives and silica sources.

Geological facts

A scratch test against ordinary steel or glass can help confirm quartz, though it may damage the specimen. Amethyst is purple quartz, while chalcedony is cryptocrystalline quartz.

Field identification & locations

Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Look for silica-like translucency, conchoidal fracture, and hardness greater than glass; laboratory testing is needed for a confident variety identification.