metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Hardness: 7 on Mohs scale. Color: White to off-white/cream. Luster: Vitreous to waxy when water-worn. Structure: Non-foliated, granular. Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- White to off-white/cream
- Luster
- Vitreous to waxy when water-worn
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Physical properties
Hardness: 7 on Mohs scale. Color: White to off-white/cream. Luster: Vitreous to waxy when water-worn. Structure: Non-foliated, granular. Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in convergent plate boundaries. This specific specimen has been further shaped and rounded by fluvial (river) or coastal erosion processes.
Uses & applications
Used as decorative landscaping stones (river rock), railway ballast, crushed stone for road construction, and occasionally in glass manufacturing if high purity.
Geological facts
Quartzite is so durable that it often outlasts the surrounding rock in weathering environments. It is harder than a steel knife and will easily scratch glass, a key diagnostic test.
Field identification & locations
Identify in the field by its hardness (7) and sugary, granular appearance on freshly broken surfaces. Found worldwide in ancient mountain belts and as river cobbles. Look for the absence of bubbling when exposed to acid (distinguishing it from marble).
