mineral

Carnelian

Carnelian (Cryptocrystalline Quartz, SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Red-orange to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: Red-orange to brownish-red
Luster: Vitreous to waxy

Identified May 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms through the infiltration of silica-rich groundwater into cavities or fractures in volcanic rock such as basalt or andesite, developing its color from iron oxide impurities. Found in geological layers ranging from Cenozoic to Jurassic age.

Uses & applications

Commonly used in jewelry for cabochons and beads, ornamental carvings, seals, and as tumbled stones for hobbyist collections.

Geological facts

Ancient civilizations such as the Romans and Greeks used carnelian for signet rings and wax seals because hot wax does not stick to it. It has been a prized gemstone for over 4,500 years.

Field identification & locations

Identify in the field by its translucent body, smooth waxy feel, and characteristic red-orange hue. Commonly found in riverbeds or coastal areas in Brazil, India, Uruguay, and various locations across the United States.