mineral

Carnelian Agate (with Quartz/Chalcedony)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, orange, white, and translucent gray; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Hardness: 6
Color: Reddish-brown, orange, white, and translucent gray
Luster: Vitreous to waxy

Identified April 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The red-brown color is caused by iron oxide (hematite) impurities. These can range from millions to several hundred million years old.

Uses & applications

Commonly used in jewelry, lapidary arts (cabochons and beads), decorative carvings, and as a popular specimen for rock collectors.

Geological facts

Carnelian has been used as a gemstone since antiquity; it was highly prized by the Egyptians and Romans for cylinder seals and signet rings because hot wax does not stick to it.

Field identification & locations

Identify in the field by its waxy luster, translucency when held to light, and smooth, water-worn exterior if found in riverbeds. Often found in gravel deposits, volcanic regions, and coastal areas.

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