Mineral

Carnelian Agate

Silicon Dioxide (SiO2) - Carnelian variety of Chalcedony

Hardness: 6.5-7 on Mohs scale; Color: Translucent orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Trigonal, cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent orange to reddish-brown
Luster: Vitreous to waxy

Identified April 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica in cavities within volcanic rocks (basalt or rhyolite) via groundwater infiltration. The orange color comes from iron oxide (hematite) impurities.

Uses & applications

Predominantly used as a gemstone in jewelry, beads, seals, and lapidary arts. Historically used for signet rings and amulets due to its durability.

Geological facts

Ancient Romans and Greeks used carnelian for signet rings because hot wax does not stick to it. It has been used as a gemstone for over 4,500 years, dating back to the Indus Valley Civilization.

Field identification & locations

Identify by its waxy luster, translucency, and warm orange-red hue. It lacks the distinct banding of 'true' agate but often presents cloudy or mottled patches. Commonly found in Brazil, India, Uruguay, and Madagascar.

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