Rock Identifier
Tumbled carnelian (Chalcedony (microcrystalline quartz), SiO₂) — gemstone
gemstone

Tumbled carnelian

Chalcedony (microcrystalline quartz), SiO₂

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange-red to reddish brown, waxy to vitreous luster, cryptocrystalline structure, and no visible cleavage. The smooth rounded shape indicates mechanical tumbling and polishing.

Identified More gemstone →
Explore Tumbled carnelian in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

Physical properties

Mohs hardness 6.5–7; translucent orange-red to reddish brown, waxy to vitreous luster, cryptocrystalline structure, and no visible cleavage. The smooth rounded shape indicates mechanical tumbling and polishing.

Formation & geological history

Carnelian forms when iron impurities color chalcedony in silica-rich volcanic cavities or sedimentary veins; deposits are mostly Cenozoic to older, with age depending on locality.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and inexpensive jewelry; polished tumbled stones are common lapidary products.

Geological facts

Its color comes mainly from dispersed iron oxides or hydroxides; heating can intensify the red-orange color, and some commercial material may be dyed.

Field identification & locations

Identify by its orange-red translucent body, fine texture, lack of cleavage, and ability to scratch glass; common sources include India, Brazil, Uruguay, Madagascar, and Namibia. Exact identification is uncertain from the image alone.