mineral

Carnelian Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: reddish-orange, brownish-red, or amber-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: reddish-orange, brownish-red, or amber-yellow
Luster: Vitreous to waxy

Identified July 1, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: reddish-orange, brownish-red, or amber-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed by the deposition of silica from groundwater into the cavities of igneous rocks such as basalt or andesite. The orange-red color is caused by iron oxide (hematite) impurities.

Uses & applications

Widely used in jewelry (beads, cabochons), ornate carvings, seals, and as a popular semi-precious stone for collectors and lapidary hobbyists.

Geological facts

Carnelian has been used for over 4,500 years. Ancient Egyptians believed it helped souls pass into the afterlife, and it was a preferred material for Roman signet rings because hot wax does not stick to it.

Field identification & locations

Look for a translucent, waxy appearance with a standard conchoidal fracture. In the field, look for river-worn or weathered nodules in volcanic regions or alluvial deposits. Common locations: India, Brazil, Uruguay, and various parts of the USA.