metamorphic
Quartzite River Pebble
Quartzite (mostly SiO2)
Hardness: 7 on Mohs scale; Color: tan to light grey with translucent patches; Luster: dull to vitreous; Crystal structure: Non-foliated granoblastic; Cleavage: None; SG: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- tan to light grey with translucent patches
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: tan to light grey with translucent patches; Luster: dull to vitreous; Crystal structure: Non-foliated granoblastic; Cleavage: None; SG: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, likely during an ancient mountain-building event. This specimen has been rounded by fluvial (river) erosion.
Uses & applications
Used as decorative landscaping stone, in construction aggregates, and for making high-silica refractories. Smooth pebbles are often used in aromatherapy or as worry stones.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges it formed in, remaining as resistant pebbles in riverbeds millions of years later. It is harder than steel and will scratch glass easily.
Field identification & locations
Identified by its sugary texture and extreme hardness (cannot be scratched by a steel knife). Commonly found in riverbeds, glacial tills, and ancient mountain belts. Look for a translucent quality when held to light.
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