mineral

Carnelian

Silicon dioxide (SiO2) with Iron Oxide impurities (Fe2O3)

Hardness: 6.5–7 on the 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 March 9, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed as a microcrystalline variety of quartz (chalcedony) in the cavities of volcanic rocks (basalt or andesite) or through the weathering of sedimentary rocks. It gets its color from iron oxide impurities. It has been used since the Neolithic period over 4,000 years ago.

Uses & applications

Used primarily in jewelry (beads, cabochons, pendants), decorative carving, and as a collectible gemstone. Historically used for signet rings and cylinder seals due to its property of not sticking to hot wax.

Geological facts

In Ancient Egypt, it was believed to assist the soul in its journey to the afterlife. It is also one of the birthstones for the month of August/Virgo. The most prized specimens come from India, where it is often treated with sun-drying or heating to deepen its red-orange hue.

Field identification & locations

Identify in the field by its translucent orange-red glow when held to light and its smooth, conchoidal fracture. Commonly found in Brazil, India, Uruguay, Madagascar, and parts of the United States like Oregon or Washington.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral