mineral
Agate (Chalcedony)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale. Color: Translucent gray, white, and brown. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (trigonal). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.64.
- Hardness
- 6
- Color
- Translucent gray, white, and brown
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Translucent gray, white, and brown. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (trigonal). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.64.
Formation & geological history
Formed primarily in volcanic and metamorphic rocks where silica-rich groundwater fills cavities (vesicles) or cracks. The silica precipitates over long periods, often in concentric layers.
Uses & applications
Commonly used for lapidary arts, jewelry (cabochons), burnishing tools, precision pendulums, and as ornamental collector specimens.
Geological facts
Agate is a variety of chalcedony. It was named by the Greek philosopher Theophrastus who discovered the stone along the shore of the Achates River in Sicily.
Field identification & locations
Identify in the field by its waxy appearance, conchoidal (shell-like) fracture, and translucent nature when held to light. Often found in riverbeds or areas with ancient volcanic activity.
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Other mineral specimens
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Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous