mineral

Tumbled brown chalcedony (likely carnelian or jasper)

Microcrystalline quartz, SiO₂ (chalcedony variety)

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to dull luster, translucent to opaque, and brown, reddish-brown, or orange coloration from iron oxides. It has cryptocrystalline quartz structure, no visible cleavage, and conchoidal fracture; the holes may be natural cavities or surface damage.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later incorporating iron staining and weathering colors. Chalcedony occurs from Precambrian to recent geological settings; this piece appears shaped and polished by tumbling.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary practice; lower-grade material is inexpensive but attractive specimens are collectible.

Geological facts

The exact variety cannot be confirmed from one photograph: brown chalcedony may be called jasper when opaque, or carnelian when distinctly red-orange. It is commonly mistaken for petrified wood or other brown tumbled stones.

Field identification & locations

Common localities include Brazil, Uruguay, India, Madagascar, Mexico, and the western United States. Field identification relies on waxy appearance, lack of cleavage, hardness sufficient to scratch glass, and a white streak; acid produces no reaction.