mineral

Polished brown chalcedony (likely carnelian or jasper)

Microcrystalline quartz, SiO₂; iron oxides produce the brown coloration

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown to reddish-brown, waxy to vitreous luster, massive cryptocrystalline structure, and no visible cleavage. The rounded surface indicates tumbling or natural water wear.

Identified September 2, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; brown to reddish-brown, waxy to vitreous luster, massive cryptocrystalline structure, and no visible cleavage. The rounded surface indicates tumbling or natural water wear.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron staining creating brown-red colors; commonly Cenozoic to older volcanic or sedimentary settings.

Uses & applications

Used for cabochons, beads, carvings, decorative stones, and inexpensive collector specimens; its durability suits jewelry.

Geological facts

Chalcedony is quartz made of extremely fine intergrown crystals. The specimen may be classified as brown carnelian if translucent, or jasper if strongly opaque and impurity-rich.

Field identification & locations

Identify by its smooth waxy surface, high hardness, conchoidal fracture, and resistance to scratching by steel; it should not fizz in dilute acid. Common sources include India, Brazil, Madagascar, Uruguay, and the western United States.