sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness: 6.5 to 7 on the Mohs scale; Color: Variegated, featuring concentric banding in pink, beige, and greenish tones; Luster: Vitreous to waxy; Crystal structure: Microcrystalline quartz (trigonal); Cleavage: None; Specific gravity: 2.58 to 2.64
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5 to 7 on the Mohs scale; Color: Variegated, featuring concentric banding in pink, beige, and greenish tones; Luster: Vitreous to waxy; Crystal structure: Microcrystalline quartz (trigonal); Cleavage: None; Specific gravity: 2.58 to 2.64
Formation & geological history
Formed by the deposition of silica from groundwater in the cavities of igneous and sedimentary rocks, typically occurring over millions of years in concentric layers.
Uses & applications
Used in ornamental objects, jewelry, tumbled stones, and precision instruments due to its durability and resistance to acids.
Geological facts
Agate is a form of chalcedony that often forms in ancient volcanic vesicles, creating mesmerizing patterns that capture environmental conditions over geological time.
Field identification & locations
Easily identified by its distinct concentric banding and waxy luster. Commonly found in regions with historic volcanic activity worldwide.
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