mineral

Carnelian Agate

Silicon Dioxide (SiO₂), a variety of Chalcedony

Hardness: 6.5-7 (Mohs scale); Color: semi-transparent orange to reddish-brown; Luster: waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: semi-transparent orange to reddish-brown
Luster: waxy to vitreous

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed in volcanic and sedimentary rocks when silica-rich groundwater fills cavities (vugs). The orange color comes from iron oxide (hematite) impurities. While found in formations of various ages, many deposits date back to the Cretaceous or Neogene periods.

Uses & applications

Primarily used in jewelry making (cabochons, beads), decorative carvings, lapidary arts, and historical use in signet rings and cylinder seals.

Geological facts

Ancient Egyptians called carnelian 'the setting sun' and believed it had protective properties. It was extensively used in the Minoan civilization and by the Romans for engraved gemstones because it does not stick to hot wax.

Field identification & locations

Identify in the field by its distinct waxy luster, translucency when held to light, and characteristic concentric banding (agate features). Commonly found in Brazil, India, Madagascar, and Uruguay. Collectors should look for vibrant color saturation and clarity.

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