metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: white to light grey; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white to light grey
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: white to light grey; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure. The specimen shown is a well-rounded pebble, shaped by fluvial (river) or coastal water erosion.
Uses & applications
Used as a decorative stone in landscaping, as an abrasive, and sometimes in construction as crushed stone or railway ballast.
Geological facts
Quartzite is so tough that it often survives through multiple cycles of erosion, outlasting the weaker rocks it was originally part of. The rounding of this specimen indicates it has spent a long time being tumbled by water.
Field identification & locations
Identify in the field by its hardness (it can scratch glass and steel) and its grainy, sandpaper-like texture before it was smoothed. Commonly found in riverbeds and mountainous regions with ancient structural upheaval.
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