mineral

Chalcedony (Fire Agate or Carnelian variety)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7 on Mohs scale; Color: Translucent orange, amber, and honey-yellow; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Color: Translucent orange, amber, and honey-yellow
Luster: Waxy to vitreous

Identified July 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed from low-temperature deposition of silica-rich groundwater in volcanic rock cavities or sedimentary environments. These specimens appear to be water-worn pebbles or lightly tumbled rough material.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons and beads), and as metaphysical or collector specimens.

Geological facts

Chalcedony has been used since the Bronze Age for seals and jewelry because it does not stick to hot wax. The warm orange tones in these specimens are caused by trace amounts of iron oxide impurities.

Field identification & locations

Identify in the field by its waxy luster, lack of visible crystals, and extreme hardness (it will scratch glass). Often found in dry washes or riverbeds in volcanic regions like the American Southwest, Brazil, or Madagascar.

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