mineral

Tumbled chalcedony (likely agate)

Microcrystalline quartz, SiO₂; chalcedony, possibly banded agate

AI-generated identification · may be incorrect

Smooth, rounded, translucent gray-white and tan areas with a waxy to glassy luster. Quartz hardness is about 7 Mohs; trigonal crystal structure, though crystals are too fine to see, and no prominent cleavage. Exact identification and specific gravity cannot be determined from the photo.

Identified October 14, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited quartz in cavities or fractures, with impurities producing the color variation; the stone was later mechanically tumbled. The specimen’s geological age and source cannot be determined visually.

Uses & applications

Commonly sold as a pocket stone, craft material, or low-cost jewelry stone; chalcedony is also used for beads, carvings, and ornamental objects.

Geological facts

Agate is a variety of chalcedony, often recognized by curved or concentric bands; this specimen lacks clearly visible banding, so the precise variety is uncertain.

Field identification & locations

Look for fine translucency, a smooth waxy surface, and hardness sufficient to scratch glass; common sources include Brazil, Uruguay, India, and the United States. The rounded finish indicates tumbling rather than natural weathering.