mineral
Quartz / Chalcedony Geode Fragment
Silicon Dioxide (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Cream, tan, beige, and white; Luster: Dull, waxy to vitreous; Crystal structure: Hexagonal/Microcrystalline; Cleavage: None (conchoidal to uneven fracture)
- Hardness
- 6
- Color
- Cream, tan, beige, and white
- Luster
- Dull, waxy to vitreous
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Cream, tan, beige, and white; Luster: Dull, waxy to vitreous; Crystal structure: Hexagonal/Microcrystalline; Cleavage: None (conchoidal to uneven fracture)
Formation & geological history
Formed in cavities within sedimentary or volcanic rocks through the precipitation of silica-rich fluids over extended geological time periods.
Uses & applications
Used primarily for lapidary work, specimen collection, landscaping, and educational purposes.
Geological facts
Weathering often exposes these silica nodules as the softer surrounding matrix rock breaks down, leaving durable quartz-rich remnants.
Field identification & locations
Can be identified by its hardness, resistance to scratching with steel, pitted surface texture, and milky white to tan microcrystalline quartz sections. Found in gravel beds, dried riverbeds, and limestone outcrops.
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