mineral

Brown botryoidal chalcedony (likely carnelian/agate)

Microcrystalline quartz, SiO₂ (chalcedony; iron-stained variety)

AI-generated identification · may be incorrect

Typically Mohs 6.5–7, translucent brown to orange with waxy-to-glassy luster and cryptocrystalline structure; no visible cleavage, conchoidal fracture, and moderate-high specific gravity (~2.6). The specimen appears rough, iron-stained, and possibly partly polished or naturally weathered.

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, depositing chalcedony in layers or botryoidal growths; iron oxides produce the brown-orange color. Formation may range from ancient volcanic-hosted deposits to younger sedimentary cavity fillings.

Uses & applications

Used as lapidary material for cabochons, beads, carvings, and decorative objects; attractive translucent pieces have modest jewelry and collecting value.

Geological facts

Carnelian is the orange-red chalcedony variety, while brown material is often sold as brown agate or jasper depending on opacity and banding. Color can be enhanced by heating or dyeing.

Field identification & locations

Look for waxy luster, conchoidal fracture, translucency, and hardness sufficient to scratch ordinary glass; it commonly occurs in volcanic cavities, gravels, and agate-bearing stream deposits. Exact identification would benefit from testing for banding, streak, and hardness.