gemstone

Tumbled orange chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂), orange variety commonly called carnelian

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, translucent to opaque, orange to reddish-orange, with a waxy to vitreous luster and no visible cleavage. The rounded shape and smooth surface indicate mechanical tumbling; the image alone cannot confirm exact variety.

Identified August 27, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later solidifying as microcrystalline quartz; iron impurities create the orange color. Deposits occur in rocks ranging from Paleozoic to Cenozoic age.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and inexpensive jewelry; tumbled pieces are popular as specimens and lapidary material.

Geological facts

Carnelian is colored mainly by iron oxides or hydroxides, and heating can intensify its red-orange color. It is a cryptocrystalline form of quartz rather than a separate mineral species.

Field identification & locations

Commonly found in volcanic terrains, alluvial gravels, and agate nodules, especially in India, Brazil, Uruguay, Madagascar, and the United States. Identify it by its orange color, waxy translucency, quartz-like hardness, and lack of cleavage; glass imitations may show bubbles.