metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: White to off-white/cream; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- White to off-white/cream
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: White to off-white/cream; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, usually during mountain-building events (orogenic). This specific specimen has been further shaped by river or coastal erosion (rounding).
Uses & applications
Used as a decorative garden stone, in construction aggregates, as a flux in glassmaking, and frequently collected as river stones or 'worry stones'.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of ridges and mountains because it resists weathering better than surrounding rocks. It was also used in prehistoric times to make stone tools when flint was unavailable.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and granular 'sugary' texture. Commonly found in riverbeds, glacial tills, and ancient mountain belts. Collectors look for smooth, well-rounded shapes.
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