mineral

Carnelian Agate

Silicon Dioxide (SiO2) - Variety of Chalcedony

Hardness: 6.5-7 (Mohs scale), Color: Reddish-orange to brownish-red, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None, Specific Gravity: 2.58-2.64.

Hardness: 6

Identified June 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed by the precipitation of silica from groundwater within cavities of volcanic rocks (lavas). The reddish color is due to impurities of iron oxide (hematite). Occurs in various geological ages and environments globally.

Uses & applications

Predominantly used as a gemstone in jewelry (beads, cabochons, rings), for ornamental carvings, seals, and as a popular specimen for mineral collectors.

Geological facts

Carnelian has been used for over 4,500 years; Ancient Egyptians called it 'the setting sun' and buried gems with the dead to aid in the journey to the afterlife. It was also widely used in Roman signet rings.

Field identification & locations

Look for a waxy luster, translucency, and conchoidal (shell-like) fracture patterns. Frequently found in riverbeds and on beaches in volcanic regions like India, Brazil, Uruguay, and the US (Pacific Northwest).

Other mineral specimens

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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