mineral

Carnelian Agate

Silicon Dioxide (SiO2) - 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 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in the gas cavities (vesicles) of volcanic rocks or sedimentary environments. The orange hue is caused by iron oxide (hematite) impurities. While possible in many ages, common specimens often date to the Tertiary or Cretaceous periods.

Uses & applications

Predominantly used for jewelry (beads, cabochons), lapidary art, ancient cylinder seals, and semi-precious gem collecting. It has been used for ornamentation since the Bronze Age.

Geological facts

Carnelian was highly valued in Ancient Egypt, where it was believed to give spirits 'power' for their journey into the afterlife. It is also the national stone of Norway.

Field identification & locations

Identify by its waxy texture, orange transluency when held to light, and lack of visible crystal grains. Often found in riverbeds or beaches where volcanic basalt has weathered away. Common locations include Brazil, India, Uruguay, and the Pacific Northwest (USA) as 'carnelian agates'.

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