mineral

Carnelian Agate

Silicon Dioxide (SiO2) - Variety: Chalcedony

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, orange, and translucent white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Reddish-brown, orange, and translucent white
Luster: Waxy to vitreous

Identified March 18, 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); Color: Reddish-brown, orange, and translucent white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The reddish hue is caused by iron oxide (hematite) impurities. While these types of formations occur throughout geological history, many common specimens are found in Eocene or younger basalt flows.

Uses & applications

Predominantly used for jewelry, lapidary carvings (like the heart shape shown), decorative cabochons, and in the manufacturing of seals or intaglios due to its hardness and toughness.

Geological facts

Carnelian has been used for over 4,500 years; it was highly prized by Ancient Egyptians who believed it had protective properties for the afterlife. This specific specimen shows distinct 'banding,' which classifies it specifically as a Carnelian Agate.

Field identification & locations

Identify by its waxy luster, translucency, and the presence of parallel or curved color bands. In the field, it is often found as rounded nodules in riverbeds or near weathered volcanic rock. Major locations include Brazil, India, Uruguay, and Madagascar.

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