metamorphic
Quartzite Pebble (Beach Stone)
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: Grayish-white with subtle red/tan staining; Luster: Dull to waxy; Crystal structure: Granular/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Grayish-white with subtle red/tan staining
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-white with subtle red/tan staining; Luster: Dull to waxy; Crystal structure: Granular/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, typically during mountain-building events. This specific specimen has been rounded and smoothed by wave action on a beach.
Uses & applications
Commonly used as crushed stone in construction, road ballast, or as decorative landscaping stones. Smooth beach pebbles are often used in interior design, aquariums, and rock painting.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges in which it forms, ending up as resilient pebbles in riverbeds and on coastlines long after other rock types have eroded away.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel knife) and its grainy, 'sugary' texture on fresh breaks. Found on beaches and riverbanks globally, especially where metamorphic bedrock is nearby.
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