mineral

Carnelian Agate

Chalcedony (SiO2 with Iron Oxide impurities)

Hardness: 6.5-7 (Mohs scale); Color: Orange, reddish-brown, brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Orange, reddish-brown, brownish-red
Luster: Vitreous to waxy

Identified April 24, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Orange, reddish-brown, brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica in cavities within volcanic rocks. The red-orange hue is caused by iron oxide (hematite) impurities. It can be found in sedimentary environments and alluvial deposits.

Uses & applications

Used primarily in jewelry (cabochons, beads), decorative carvings, and as a semi-precious collector's mineral.

Geological facts

Carnelian was highly prized in ancient times; ancient Romans used it for signet rings and wax seals because the wax doesn't stick to the smooth surface of the stone.

Field identification & locations

Identified by its translucent to semi-opaque reddish-orange color and conchoidal fracture. Often found as rounded pebbles in stream beds or coastal areas in India, Brazil, and Uruguay.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral