mineral
Carnelian
Silicon dioxide (SiO2) - variety of Chalcedony
Hardness: 6.5-7 (Mohs scale); Color: Orange, reddish-brown, or brownish-red; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Orange, reddish-brown, or brownish-red
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Orange, reddish-brown, or brownish-red; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Forms in volcanic rocks where silica-rich groundwater percolates through cavities, depositing layers of microcrystalline quartz. Red color is due to iron oxide impurities.
Uses & applications
Primarily used in jewelry (cabochons and beads), decorative carvings, and seal stones. Historically used for signet rings.
Geological facts
In ancient times, carnelian was believed to protect against evil spirits and was found in ancient Egyptian tombs. It was also used in Roman signet rings because hot wax does not stick to it.
Field identification & locations
Identify by its translucent, waxy appearance and warm reddish-orange hue. It lacks the banding seen in Agate. It is commonly found in India, Brazil, Uruguay, and Madagascar.
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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)
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