Rock Identifier
Tumbled carnelian (orange chalcedony) (Carnelian, a microcrystalline variety of quartz (SiO₂), commonly colored by iron oxides) — gemstone
gemstone

Tumbled carnelian (orange chalcedony)

Carnelian, a microcrystalline variety of quartz (SiO₂), commonly colored by iron oxides

AI-generated identification · may be incorrect

Translucent orange-red, smooth and polished, with waxy to glassy luster and no visible cleavage. Mohs hardness 6.5–7; specific gravity about 2.60–2.65; cryptocrystalline structure.

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Physical properties

Translucent orange-red, smooth and polished, with waxy to glassy luster and no visible cleavage. Mohs hardness 6.5–7; specific gravity about 2.60–2.65; cryptocrystalline structure.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later acquiring its orange color from iron. It is generally associated with Cenozoic and older volcanic or sedimentary deposits.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and inexpensive jewelry. Small tumbled pieces are usually decorative rather than highly valuable.

Geological facts

The photograph strongly resembles dyed or natural carnelian; color alone cannot confirm which. Natural specimens often show subtle bands, cloudy zones, or uneven translucency.

Field identification & locations

Commonly found in India, Brazil, Uruguay, Madagascar, Germany, and the United States. Check for glass-like hardness, translucency at the edges, and absence of bubbles; a gemological test is needed to distinguish dyed chalcedony or glass.