mineral
Agate (Carnelian / Chalcedony)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Honey-yellow, translucent brown to orange; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64
- Hardness
- 6
- Color
- Honey-yellow, translucent brown to orange
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Honey-yellow, translucent brown to orange; Luster: Waxy to vitreous; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64
Formation & geological history
Forms primarily within cavities (geodes) of volcanic igneous rocks or sedimentary formations as silica-rich water precipitates layer by layer over time.
Uses & applications
Popular for gemstone lapidary work, tumbling, jewelry making, ornamental carvings, and rock collecting.
Geological facts
Agates are microcrystalline varieties of quartz. The translucent honey-yellow to orange coloration is typically due to iron oxide impurities embedded within the silica matrix.
Field identification & locations
Look for a waxy, smooth texture, conchoidal fracture surfaces, high translucency under light, and a high hardness that scratches glass. Commonly found along gravel bars, riverbeds, and volcanic rock outcrops worldwide.
