mineral
Quartz Pebble (Geode Nodules / Stream-Rounded Quartz)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: Off-white, grey, milky to translucent. Luster: Vitreous to waxy when weathered. Crystal System: Trigonal. Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Off-white, grey, milky to translucent
- Luster
- Vitreous to waxy when weathered
Identified More mineral →
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Physical properties
Hardness: 7 on Mohs scale. Color: Off-white, grey, milky to translucent. Luster: Vitreous to waxy when weathered. Crystal System: Trigonal. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through precipitation of silica in cavities within igneous or sedimentary rocks, or as quartz veins that were subsequently eroded and rounded by water action in rivers, streams, or glacial processes.
Uses & applications
Used primarily in lapidary work (tumbling, cutting), as decorative garden stones, in silica glass production, or cracked open by collectors looking for internal geode cavities.
Geological facts
Many rounded quartz nodules look like ordinary stream rocks on the outside, but can harbor hollow cavities lined with sparkling quartz, amethyst, or agate crystals inside.
Field identification & locations
Identified by its high hardness (scratches glass/steel easily), rounded shape, and waxy or sugary texture. Commonly found in stream beds, gravel pits, glacial till, and desert wash regions.
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