metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white, grey, or tan; Luster: vitreous to dull; Crystal Structure: non-foliated granoblastic; Cleavage: none; Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- typically white, grey, or tan
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, grey, or tan; Luster: vitreous to dull; Crystal Structure: non-foliated granoblastic; Cleavage: none; Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing recrystallization of quartz grains. These rounded pebbles are often found in riverbeds or beaches where water erosion has smoothed them over centuries.
Uses & applications
Used as a decorative landscape stone, in road construction, as railroad ballast, and sometimes in low-cost jewelry or as 'worry stones' when polished.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks in mountainous areas, forming the caps of ridges. It is often harder and more durable than the parent sandstone from which it originated.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and its sugary texture on fractured surfaces. Primarily found in areas of ancient mountain building or in alluvial deposits.
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