sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on Mohs scale; Color: Variable, often banded with white, grey, blue, or brown; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
- Hardness
- 6
- Color
- Variable, often banded with white, grey, blue, or brown
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Variable, often banded with white, grey, blue, or brown; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Used for jewelry, ornamental objects, carvings, and sometimes in precision instruments due to its durability.
Geological facts
Agate is one of the most popular materials used in art carving and tumbling due to its unique concentric banding patterns.
Field identification & locations
Easily identified by its distinct banding and waxy luster; found worldwide in river gravels, volcanic regions, and sedimentary deposits.
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