mineral

Carnelian Agate

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3) inclusions

Hardness: 6.5-7 on the Mohs scale. Color: Translucent reddish-orange to brownish-red. Luster: Vitreous to waxy. Crystal Structure: Trigonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

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

Identified March 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks such as basalt. The characteristic orange-red color comes from iron oxide impurities that migrate through the porous silica during or after formation. Found in geological formations ranging from the Cretaceous to recent quaternary deposits.

Uses & applications

Primarily used in jewelry (beads, cabochons), lapidary art, and as decorative tumbling stones. Traditionally used for making signet rings and cameos due to its durability and how easily it releases from hot wax.

Geological facts

Ancient Romans used carnelian for seal rings, and the Prophet Muhammad was said to wear a carnelian seal ring. It was also highly prized in Ancient Egypt, where it was associated with the blood of Isis and used in elaborate pectorals and amulets to protect the dead in the afterlife.

Field identification & locations

Field identification involves looking for translucent, reddish-orange stones with a waxy luster and conchoidal (shell-like) fracture patterns. It is commonly found in India, Brazil, Uruguay, and Madagascar. Collectors should look for uniformity of color and higher translucency.

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