mineral

Carnelian (Chalcedony)

SiO2 (Silicon Dioxide - Microcrystalline Quartz)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to deep brownish-red; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Translucency: Translucent when backlit.

Hardness: 6
Color: Reddish-orange to deep brownish-red
Luster: Waxy to vitreous

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed at low temperatures by the deposition of silica-rich solutions in cavities and fissures within igneous or sedimentary host rocks. Common in basaltic lavas and alluvial gravel deposits.

Uses & applications

Widely used in lapidary work, gemstones, cabochons, carved beads, seals, and ornamental jewelry. Highly valued as a collector specimen and metaphysical crystal.

Geological facts

Carnelian has been used in jewelry making for over 4,500 years, dating back to ancient Sumerian, Egyptian, and Roman civilizations, where it was frequently carved into signet rings and protective amulets.

Field identification & locations

Look for strong orange-red translucency under backlighting, smooth waxy surface texture, and absence of distinct banding (which would classify it as agate). Minas Gerais, Brazil, is world-renowned for producing high-grade agate, carnelian, and quartz minerals.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

sedimentary

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

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Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

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