mineral

Carnelian

Silicon Dioxide (SiO2) - variety of Chalcedony

Hardness: 6.5-7 (Mohs scale), Color: Brownish-red to orange, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None, Specific Gravity: 2.58–2.64

Hardness: 6

Identified March 20, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Brownish-red to orange, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline), Cleavage: None, Specific Gravity: 2.58–2.64

Formation & geological history

Formed in cavities and veins of volcanic rocks (basalts and rhyolites) through the deposition of silica-rich groundwaters. Its reddish color comes from iron oxide impurities.

Uses & applications

Predominantly used as a gemstone for jewelry, in lapidary work for cabochons and beads, and historically used for making cylinder seals and signet rings.

Geological facts

Carnelian was highly valued in Ancient Egypt, where it was thought to provide protection for the soul in the afterlife. It is the modern birth stone for July in some cultures and was used by the Romans for seal rings because hot wax does not stick to it.

Field identification & locations

Identified by its translucent brownish-red color and waxy surface when polished. Found commonly in Brazil, India, Uruguay, and Madagascar. Collectors should look for uniform transparency and deep, saturated orange-red hues.

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