mineral
Blue Onyx (Agate)
Cryptocrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs. Color: Deep blue to translucent teal. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 2.58-2.64.
- Hardness
- 6
- Color
- Deep blue to translucent teal
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs. Color: Deep blue to translucent teal. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal). Cleavage: None. Specific Gravity: 2.58-2.64.
Formation & geological history
Formed from volcanic activity where silica-rich groundwater fills gas cavities (vesicles) in igneous rock. Over time, these fluids precipitate layers of microscopic quartz crystals.
Uses & applications
Commonly used in jewelry, ornamental carvings, meditation stones, and decorative furniture inlays.
Geological facts
Most deep blue onyx in the market is natural chalcedony or agate that has been treated or dyed to enhance its color, as intense blue is rare in pure microcrystalline quartz.
Field identification & locations
Identified by its waxy luster and smooth, conchoidal fracture. Collectors should look for internal banding patterns. Found in Brazil, India, and Madagascar.
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Mineral/Rock
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Green Apatite on Albite
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mineral