Properties
| Category | Tectosilicate minerals |
|---|---|
| Formula | SiO2 (silicon dioxide) |
| Crystal system | Trigonal (quartz), monoclinic (moganite) |
| Color | Reddish, orange, brownish |
| Cleavage | Absent |
| Fracture | Uneven, splintery, conchoidal |
| Mohs scale hardness | 6.5–7.0 |
| Luster | Waxy to resinous |
| Streak | White |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 2.58–2.64 |
From the Wikipedia article
Carnelian is a brownish-red mineral commonly used as a semiprecious stone. Similar to carnelian is sard, which is generally harder and darker; the difference is not rigidly defined, and the two names are often used interchangeably. Both carnelian and sard are varieties of the silica mineral chalcedony colored by impurities of iron oxide. The color can vary greatly, ranging from pale orange to an intense almost-black coloration. Significant localities include Yanacodo, Peru and Ratnapura, Sri Lanka. It has been found in Indonesia, Brazil, India, Iran, Russia (Siberia), and Germany.
Source
Source record: crystal-compendium/carnelian/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Carnelian — revision id 1360760061. Text and properties from Wikipedia, licensed CC BY-SA 4.0.