mineral
Chalcedony (Common Agate)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Translucent grey, lavender, and tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; Break: Conchoidal
- Hardness
- 6
- Color
- Translucent grey, lavender, and tan
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Translucent grey, lavender, and tan; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline (Trigonal/Monoclinic); Cleavage: None; Break: Conchoidal
Formation & geological history
Formed through the deposition of silica from groundwater in cavities of volcanic and sedimentary rocks. This specimen appears water-worn, likely found in a riverbed or coastal area.
Uses & applications
Commonly used for lapidary work, jewelry making (cabochons), and as a collector's specimen. In industry, it can be used for mortars and pestles due to its hardness.
Geological facts
Chalcedony is a cryptocrystalline form of silica, meaning its crystals are too small to be seen with a standard microscope. When it exhibits banding, it is specifically called Agate.
Field identification & locations
Identify in the field by its waxy luster, conchoidal (shell-like) fracture, and inability to be scratched by a steel knife. Common in volcanic regions and gravel deposits worldwide.
