mineral

Tumbled carnelian/chalcedony

Microcrystalline quartz (SiO₂), iron-oxide-stained chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-brown and gray, with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no cleavage, conchoidal fracture, and typically specific gravity near 2.6.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures, later acquiring orange-red coloration from dispersed iron oxides. The specimen is likely a naturally weathered or human-tumbled pebble; its precise geological age cannot be determined from the image.

Uses & applications

Used for beads, cabochons, carvings, ornamental stone, and small polished collectibles; common material has modest commercial value.

Geological facts

Carnelian is an orange variety of chalcedony, closely related to sard and agate. Heating can intensify its red-orange color by oxidizing iron.

Field identification & locations

Identify it by its waxy translucence, smooth conchoidal fracture, lack of visible quartz grains, and orange iron staining; a steel file should not easily scratch it. Common sources include India, Brazil, Uruguay, Madagascar, and river gravels worldwide.