gemstone

Polished carnelian/chalcedony pebble

Chalcedony, microcrystalline quartz (SiO₂), likely iron-stained orange-red variety

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange, red, cream, and brown banding with a waxy-to-glassy luster. Cryptocrystalline quartz has no visible cleavage and typically conchoidal fracture; specific gravity is about 2.58–2.64.

Identified September 15, 2026More gemstone →

Explore Polished carnelian/chalcedony pebble in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later colored by iron oxides; commonly Cenozoic to older, depending on host rock. This specimen is tumbled and polished.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and historical seals; durable enough for jewelry and small decorative objects.

Geological facts

Carnelian is the orange-red chalcedony variety, while paler or banded material may be called sard or agate. Heat treatment can intensify its red-orange color.

Field identification & locations

Identify by its smooth waxy luster, translucency, hardness, and lack of cleavage; it should resist scratching from steel but not quartz. Common sources include India, Brazil, Uruguay, Madagascar, and Namibia.