mineral
Agate
Chalcedony (SiO2)
Hardness: 6.5-7 on the Mohs scale; Color: Varies widely including grey, white, blue, brown, red; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz)
- Hardness
- 6
- Color
- Varies widely including grey, white, blue, brown, red
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Varies widely including grey, white, blue, brown, red; 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, often occurring in concentric bands over millions of years
Uses & applications
Used primarily in jewelry, ornamental carvings, polished display specimens, and industrial bearings
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
Identified by its distinctive concentric banding and waxy luster; commonly found worldwide in volcanic rock cavities or ancient lava flows
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
sedimentary
Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
mineral
Schist
Schist
Metamorphic
Septarian Pebble
Septarian nodule / Concretion
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral