mineral
Quartz (Gravel Pebble)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Colorless to translucent; Luster: Vitreous/Glassy; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Colorless to translucent
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 7 on Mohs scale; Color: Colorless to translucent; Luster: Vitreous/Glassy; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Forms in nearly all geological environments, particularly igneous and metamorphic rocks, through crystallization from magma or hydrothermal precipitate. Found globally in all geological ages.
Uses & applications
Raw industrial quartz is used in glassmaking, abrasives, and electronics (piezoelectric properties). Rounded pebbles are used in landscaping and as aggregate in construction.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Small, rounded pebbles like this are often the result of long-term weathering and transport by water in rivers or beaches.
Field identification & locations
Identify by its hardness (it can scratch glass), its lack of cleavage, and glassy appearance. Common in riverbeds, beaches, and soil worldwide.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock