mineral

Tumbled chalcedony or quartz fragment

Microcrystalline quartz, SiO₂ (probable chalcedony)

AI-generated identification · may be incorrect

Small translucent brown-gray piece with a waxy to slightly vitreous luster and likely conchoidal fracture; quartz hardness is about 7 Mohs, with no cleavage and specific gravity near 2.6. The rounded edges suggest tumbling or natural abrasion, though the image is insufficient for certainty.

Identified August 13, 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; formation ages range from recent deposits to ancient volcanic environments. Brown coloration may result from iron oxides or included material.

Uses & applications

Used for carvings, beads, cabochons, and decorative specimens; low-grade material is also used as aggregate or ornamental stone.

Geological facts

Chalcedony is a variety of quartz composed of intergrowths of microscopic quartz crystals and may grade into jasper or agate.

Field identification & locations

Commonly found in volcanic terrains, alluvial gravels, and silica-rich cavities worldwide. A glassy conchoidal fracture, hardness sufficient to scratch ordinary glass, and lack of cleavage support quartz identification; a scratch test or magnification would help distinguish it from glass or slag.