mineral

Likely tumbled chalcedony or jasper pebble

Microcrystalline quartz (SiO₂), possibly iron-stained jasper

AI-generated identification · may be incorrect

Small polished/tumbled pebble with blue-gray translucent areas and a brown iron-oxide-rich patch; vitreous to waxy luster, no obvious cleavage, Mohs hardness about 6.5–7, and specific gravity near 2.6. The image is insufficient to confirm exact variety.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; brown coloration usually comes from hematite or goethite. Formation may range from Cenozoic to much older, depending on the host deposit.

Uses & applications

Used for beads, cabochons, carvings, and ornamental stone; attractive small pieces are collected as lapidary material.

Geological facts

The blue-gray appearance may reflect chalcedony, while the brown zone suggests jasper-like opaque silica or iron staining. Polishing can make translucent quartz varieties appear more saturated.

Field identification & locations

Common sources include volcanic terrains in Brazil, Uruguay, India, Madagascar, Mexico, and the western United States. Confirm with a hardness test against glass and examination for uniform microcrystalline texture; avoid scratching valuable pieces.