Mineral
Agate
SiO2 (Silicon dioxide, chalcedony variety)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs), Color: Translucent to opaque, often banded, varying colors including orange, white, and red in this specimen. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None.
- Hardness
- 6
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Translucent to opaque, often banded, varying colors including orange, white, and red in this specimen. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None.
Formation & geological history
Forms in volcanic rocks or ancient lavas as nodules or geodes, formed by the deposition of silica from groundwater in cavities.
Uses & applications
Used primarily in jewelry, ornamental objects, carving, and as a collector's stone. Also used historically for hardstone carving.
Geological facts
Agate is a variety of chalcedony characterized by its fineness of grain and brightness of color. It was highly valued in antiquity as a talisman or amulet.
Field identification & locations
Identify by its waxy luster, hardness (scratches glass), and often banded appearance. Translucency is a key feature separating it from jasper. Commonly found worldwide, especially in Brazil, Uruguay, and parts of the US (like Lake Superior agate).
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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
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
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Granite
Granite (Phaneritic intrusive igneous rock)
igneous
Septarian Pebble
Septarian nodule / Concretion
sedimentary