mineral

Carnelian Agate

Silicon Dioxide (SiO2) - Variety of Chalcedony

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange, brownish-red to amber; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58–2.64.

Hardness: 6
Color: Reddish-orange, brownish-red to amber
Luster: Vitreous to waxy

Identified March 14, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange, brownish-red to amber; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58–2.64.

Formation & geological history

Formed in low-temperature hydrothermal environments, typically as fillings in cavities (vesicles) of volcanic rocks or sedimentary deposits. The red color is caused by the presence of iron oxide (hematite) impurities.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, intaglios, and by collectors. Historically used for signet rings and seals due to its property of not sticking to hot wax.

Geological facts

Ancient Egyptians referred to carnelian as 'the setting sun' and buried it with the dead to assist them in the afterlife. It was also one of the twelve stones in the breastplate of the High Priest in Biblical accounts.

Field identification & locations

Identify in the field by its distinct translucent orange-red color and waxy luster. Look for it in riverbeds or volcanic regions. It lacks the internal banding of true banded agate but often occurs in similar geological settings. Found globally in Brazil, India, Uruguay, and Madagascar.

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