mineral
Carnelian
Chalcedony (SiO2) with iron oxide impurities
Hardness: 6.5-7 (Mohs scale); Color: Brownish-red to orange; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Brownish-red to orange
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brownish-red to orange; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Formed in low-temperature hydrothermal environments where silica-rich fluids deposit in cavities of volcanic rocks. The orange-red color comes from hematite or iron oxide inclusions.
Uses & applications
Commonly used in jewelry, as cabochons, for beads, and in lapidary art such as intaglio carving and seal-making.
Geological facts
Carnelian is one of the oldest gemstones in history; it was used by the Ancient Egyptians for amulets and by Romans for signet rings because hot wax doesn't stick to its smooth surface.
Field identification & locations
Identify by its characteristic warm orange-red translucency and waxy luster. In the field, look for smooth, rounded pebbles in riverbeds or volcanic areas. Small, rough garnets or jaspers can look similar, but carnelian is notably more translucent.
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