mineral
Quartz Pebble (Geode Fragment / Druzy Cavity)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: Translucent grayish-tan with microcrystalline quartz druze. Luster: Vitreous to waxy. Crystal structure: Hexagonal/trigonal. Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Translucent grayish-tan with microcrystalline quartz druze
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: Translucent grayish-tan with microcrystalline quartz druze. Luster: Vitreous to waxy. Crystal structure: Hexagonal/trigonal. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed via precipitation of silica-rich fluids within rock cavities or gas bubbles (vesicles), which were later weathered, eroded, and rounded by stream or beach action into river pebbles.
Uses & applications
Commonly collected as river rocks, used in landscaping, tumbling for rock hounding, and educational specimens.
Geological facts
Small cavities lined with tiny sparkly crystals inside rounded beach or river pebbles are often referred to as mini-geodes or druzy cavities, preserving internal micro-crystals despite external river wear.
Field identification & locations
Look for rounded, smooth quartz-rich river pebbles that feature small open pockets or vugs containing sparkling micro-crystals when held up to direct sunlight.
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