mineral

Tumbled brown chalcedony (likely carnelian or jasper)

Microcrystalline quartz, SiO₂; iron oxides produce the brown-red coloration

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent to opaque brown with reddish tones, glassy to waxy luster, and no visible cleavage. The smoothly polished surface indicates a tumbled specimen; specific gravity is about 2.60–2.65.

Identified September 18, 2026More mineral →

Explore Tumbled brown chalcedony (likely carnelian or jasper) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities, fractures, or vesicles and precipitates cryptocrystalline quartz, commonly in volcanic rocks. It may range from young placer material to Paleozoic or older host-rock deposits, depending on locality.

Uses & applications

Used for cabochons, beads, carvings, lapidary ornaments, and inexpensive jewelry; jasper varieties are also used decoratively.

Geological facts

Carnelian is the translucent red-orange variety of chalcedony, while more opaque brown material is generally called jasper. Color commonly results from dispersed hematite or limonite.

Field identification & locations

Look for uniform cryptocrystalline texture, waxy/glassy polish, absence of cleavage, and resistance to scratching by steel; exact identification requires translucency and locality information. Common sources include Brazil, India, Uruguay, Madagascar, and the western United States.