Rock Identifier
Tumbled orange chalcedony or carnelian (Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/carnelian) — mineral
mineral

Tumbled orange chalcedony or carnelian

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/carnelian

AI-generated identification · may be incorrect

Small translucent orange-brown fragment with a waxy to dull luster and irregular fracture; quartz hardness is about 7 Mohs, with no obvious cleavage and specific gravity near 2.60. The photograph cannot confirm the exact variety or whether it is naturally rounded.

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Physical properties

Small translucent orange-brown fragment with a waxy to dull luster and irregular fracture; quartz hardness is about 7 Mohs, with no obvious cleavage and specific gravity near 2.60. The photograph cannot confirm the exact variety or whether it is naturally rounded.

Formation & geological history

Silica-rich groundwater deposited microscopic quartz fibers in cavities or fractures, while iron oxides produced the orange-red color; such material commonly formed in volcanic rocks during the Cenozoic or older periods. Exact age and locality require provenance or testing.

Uses & applications

Used as inexpensive cabochons, beads, carvings, lapidary material, and ornamental stone; small fragments have modest collecting value.

Geological facts

Carnelian is the orange-red variety of chalcedony, and color may intensify after heating. It can resemble orange glass, resin, citrine, or fire opal.

Field identification & locations

Common in Brazil, India, Uruguay, Madagascar, Namibia, and the United States. Check for a waxy appearance, cool feel, hardness sufficient to scratch glass, and lack of bubbles; definitive identification may require microscopy or spectroscopy.