gemstone
Agate
Silicon Dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness: 6.5 to 7 on the Mohs scale; Color: Varies widely including brown, white, red, gray, pink, black, and yellow with distinctive concentric banding; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz)
- Hardness
- 6
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5 to 7 on the Mohs scale; Color: Varies widely including brown, white, red, gray, pink, black, and yellow with distinctive concentric banding; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz)
Formation & geological history
Formed by the deposition of silica from groundwater in the cavities of igneous and sedimentary rocks, typically over millions of years.
Uses & applications
Used primarily in jewelry, ornamental carvings, decorative objects, and historically for precision instruments like mortar and pestles due to its hardness.
Geological facts
Agate was named by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shoreline of the Achates River in Sicily.
Field identification & locations
Easily identified by its distinct concentric color bands and waxy luster. Commonly found worldwide, notably in Brazil, Uruguay, India, and parts of the United States like Oregon and Lake Superior.
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