Rock Identifier
Carnelian (SiO2 (Silicon Dioxide, variety of Chalcedony)) — mineral
mineral

Carnelian

SiO2 (Silicon Dioxide, variety of Chalcedony)

Hardness: 6.5-7 on Mohs scale; Color: Ranges from pale orange to intense deep reddish-orange; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Hardness
6
Color
Ranges from pale orange to intense deep reddish-orange
Luster
Vitreous to waxy
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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Ranges from pale orange to intense deep reddish-orange; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Formation & geological history

Forms primarily as a secondary mineral in volcanic or sedimentary rocks. It develops through the deposition of silica from groundwater within cavities, often colored by iron oxide (hematite) impurities. It can be found in ancient geode formations or as river-worn pebbles.

Uses & applications

Used extensively in jewelry as gemstones (cabochons, beads), decorative carvings, wax seals, and in crystal healing practices. Historically used for signet rings and amulets.

Geological facts

Carnelian was highly prized by the Ancient Egyptians who called it 'the setting sun' and believed it had protective powers. The color can often be enhanced or shifted to deeper reds by heating the stone in the sun or kilns.

Field identification & locations

Identify by its translucent reddish-orange hue, lack of banding (which distinguishes it from sardonyx/agate), and its ability to scratch glass. Commonly found in Brazil, India, Madagascar, and Uruguay. Look for tumbled, water-worn pebbles in stream beds in volcanic regions.

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mineral