Properties
| Category | Tectosilicate minerals |
|---|---|
| Formula | Silica (silicon dioxide, SiO2) |
| Crystal system | Trigonal (quartz), monoclinic (moganite) |
| Color | Red to orange, brown, iridescent flashes |
| Crystal habit | Frequently botryoidal, microgranular aggregates |
| Cleavage | Absent |
| Fracture | Uneven, splintery, conchoidal |
| Mohs scale hardness | 6.5-7 |
| Luster | Waxy, vitreous |
| Streak | White |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 2.60- 2.64 |
From the Wikipedia article
Fire agate is a variety of chalcedony that displays fire-like iridescent flashes. It is found only in certain areas of central and northern Mexico and the southwestern United States. Despite its name, it is not a true agate, since it typically does not have bands. Approximately 24-36 million years ago, during the Tertiary Period, these areas were subjected to massive volcanic activity. Fire agates were formed when hot water, saturated with silica and iron oxide, filled cracks and cavities in the surrounding rock and solidified into chalcedony layered with crystallized iron oxide.
Source
Source record: crystal-compendium/fire-agate/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Fire_agate — revision id 1353116660. Text and properties from Wikipedia, licensed CC BY-SA 4.0.