gemstone
Fire Agate
Silicon Dioxide (Chalcedony with Limonite inclusions), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale with a botryoidal habit and waxy to vitreous luster. Displays iridescent play of color caused by light interference.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale with a botryoidal habit and waxy to vitreous luster. Displays iridescent play of color caused by light interference.
Formation & geological history
Formed in volcanic and hydrothermal environments when hot, silica-rich water filled cavities in rock over millions of years.
Uses & applications
Used primarily as a semi-precious gemstone in bespoke jewelry and collected by mineral enthusiasts.
Geological facts
The iridescent fire effect is caused by thin layers of limonite crystals acting as a diffraction grating. It is found almost exclusively in the southwestern United States and northern Mexico.
Field identification & locations
Identify by its distinct grape-like botryoidal surface and multi-colored flash under direct light. Commonly sourced from localities like Aguascalientes, Mexico, and Arizona.
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