mineral
Carnelian (Carnelian Agate)
Silicon Dioxide (SiO2) - variety of Chalcedony
Hardness: 6.5-7 Mohs; Color: brownish-red to orange; Luster: vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.58-2.64.
- Hardness
- 6
- Color
- brownish-red to orange
- Luster
- vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: brownish-red to orange; Luster: vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.58-2.64.
Formation & geological history
Formed through the deposition of silica in cavities of volcanic rocks (lavas) or sedimentary rocks. The red coloring comes from iron oxide (hematite) impurities. It can be found in various geological ages ranging from the Cretaceous to the modern era.
Uses & applications
Used primarily as a semi-precious gemstone in jewelry (beads, cabochons), for ornamental carvings, signet rings, and as a popular specimen for crystal collectors.
Geological facts
Carnelian was highly prized in ancient times; it was used by Egyptians in amulets to represent the setting sun and by Romans for seal rings because wax does not stick to it. The name is derived from the Latin 'carne' meaning flesh.
Field identification & locations
Identify by its translucent to semi-opaque orange-red hue and waxy luster. It lacks the internal banding of 'true' agate but is often found in similar environments. Common locations include Brazil, India, Madagascar, and Uruguay.
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Arenite (SiO2 based)
sedimentary
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Metamorphic
Epidote
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metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock