gemstone
Carnelian (Polished Cabochon)
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Reddish-orange to brownish-red
- Luster
- Vitreous to waxy
Identified More gemstone →
Explore Carnelian (Polished Cabochon) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal (Cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Formed from the deposition of silica from groundwater in volcanic rock cavities or sedimentary environments. The red color is caused by iron oxide (hematite) impurities. Most commercial carnelian is heat-treated to enhance its color.
Uses & applications
Used primarily in jewelry as cabochons, beads, and engravings. Historically used for seal stones, signet rings, and talismans.
Geological facts
Ancient Egyptians called carnelian 'the setting sun' and used it in the burial rituals of pharaohs. It was also the most popular material for Roman signet rings because hot wax does not stick to it.
Field identification & locations
Identify by its translucent to semi-opaque appearance and warm orange-red hue. Commonly found in Brazil, India, Uruguay, and Madagascar. Collectors look for consistency in color and lack of visible inclusions.
More like this
Other gemstone specimens
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Emerald
Beryl (Be₃Al₂Si₆Oထ₈) with Chromium/Vanadium impurities
gemstone
Amber
Succinite (Organic Gemstone)
mineral
Citrine
Silicon Dioxide (SiO2) with iron impurities
mineral
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
mineral
Amber
Succinrite (Organic Gemstone)
mineraloid