gemstone
Carnelian Agate
Cryptocrystalline Quartz (SiO2) with Iron Oxide impurities
Hardness: 6.5-7 (Mohs); Color: Red-orange to brownish-red; Luster: Vitreous to waxy; Structure: Hexagonal (trigonal); Translucent to semi-opaque.
- Hardness
- 6
- Color
- Red-orange to brownish-red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Red-orange to brownish-red; Luster: Vitreous to waxy; Structure: Hexagonal (trigonal); Translucent to semi-opaque.
Formation & geological history
Formed in cavities of volcanic rocks through the deposition of silica from groundwater; its red color comes from iron oxide (hematite) impurities. Generally found in Tertiary volcanic flows.
Uses & applications
Primarily used in jewelry as cabochons, beads, and carvings. Also popular in metaphysical collections and ancient intaglios.
Geological facts
Carnelian is one of the oldest gemstones in history; it was used by the Ancient Egyptians for amulets and in Roman times for signet rings because hot wax does not stick to it.
Field identification & locations
Identify by its characteristic warm orange-red color and banded patterns common to agates. Common sources include India, Brazil, Uruguay, and Madagascar. Look for uniform translucency.
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