sedimentary
Yellow Agate (Banded Chalcedony)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs. Color: Yellow, honey, brown, and white banding. Luster: Vitreous to waxy. Structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.58-2.64.
- Hardness
- 6
- Color
- Yellow, honey, brown, and white banding
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs. Color: Yellow, honey, brown, and white banding. Luster: Vitreous to waxy. Structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.58-2.64.
Formation & geological history
Formed as a secondary mineral in volcanic rock cavities (vesicles) or sedimentary rock through the precipitation of silica from groundwater. Often found in Cenozoic deposits.
Uses & applications
Primarily used for jewelry, lapidary art, tumble-polishing, and as decorative gemstones/pendants.
Geological facts
Agate is a variety of chalcedony that shows distinct color banding. The name 'Agate' comes from the Achates River in Sicily, where agates were first discovered in ancient times.
Field identification & locations
Identify by its waxy luster, conchoidal fracture, and concentric or parallel banding when polished. Often found in riverbeds or near ancient volcanic activity.
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