mineral
Carnelian Agate
Chalcedony (SiO2) with iron oxide inclusions
Hardness: 6.5-7 Mohs; Color: Orange-red to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Fracture: Conchoidal; Translucent to semi-opaque.
- Hardness
- 6
- Color
- Orange-red to brownish-red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Orange-red to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Fracture: Conchoidal; Translucent to semi-opaque.
Formation & geological history
Formed through the deposition of silica from groundwater in cavities of igneous rocks, particularly volcanic lavas. The reddish hue is caused by the presence of hematite or iron oxide impurities during cooling.
Uses & applications
Widely used as a gemstone in jewelry (beads, cabochons, rings), for carving seals and intaglios, and popular among mineral collectors for its vibrant color.
Geological facts
Carnelian has been used for over 4,500 years; ancient Egyptians believed it had protective properties and used it in burial amulets and the famous golden mask of Tutankhamun.
Field identification & locations
Identify in the field by its distinct waxy luster and shell-like (conchoidal) fracture. It is commonly found in India, Brazil, Uruguay, and Madagascar. Collectors look for uniform color and high translucency.
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