gemstone

Orange chalcedony or carnelian pebble

Microcrystalline quartz, SiO₂; orange-red chalcedony is commonly called carnelian

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent to opaque orange, peach, or reddish body with a waxy to vitreous luster. Quartz has a trigonal crystal structure, but chalcedony is cryptocrystalline and lacks visible cleavage.

Identified September 5, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later becoming microcrystalline quartz; iron oxides produce the orange-red color. Individual pieces may range from young alluvial pebbles to ancient volcanic-hosted material.

Uses & applications

Used for cabochons, beads, carvings, seals, and tumbled stones; durable enough for jewelry but generally inexpensive unless strongly colored and translucent.

Geological facts

Carnelian is an agate-family variety of chalcedony, and its color may deepen with gentle heating. The specimen’s smooth shape suggests natural water wear or tumbling.

Field identification & locations

Identify by its uniform orange color, waxy appearance, lack of cleavage, and ability to scratch glass; it should not fizz in dilute acid. Common sources include India, Brazil, Uruguay, Madagascar, and Indonesia.