mineral

Carnelian Agate

Carnelian (Silicon Dioxide - SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: Translucent orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Trigonal, microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

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

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in low-temperature silica-rich groundwater environments, typically filling cavities or veins in igneous rocks like basalt. The red color is caused by impurities of iron oxide (hematite). Specimens can be of various geological ages, often from the Cretaceous or Tertiary periods.

Uses & applications

Primary use is in semi-precious jewelry (beads, cabochons, carvings) and lapidary arts. Historically used for signet rings and wax seals because hot wax does not stick to it.

Geological facts

Carnelian was believed by ancient Egyptians to be the 'blood of Isis' and was used in the funerary 'Book of the Dead' to assist the soul's journey. It is also one of the birthstones for the zodiac sign Virgo.

Field identification & locations

Identify by its waxy luster, translucency, and warm orange-red hue. It can be found in gravel beds of rivers or weathered out of volcanic deposits. Major global locations include India, Brazil, Uruguay, and Madagascar.