metamorphic
Quartzite Pebble
Quartzite (SiO2 with minor iron impurities)
Hardness: 7 on Mohs scale; Color: tan, reddish-brown, and white with mottled iron staining; Luster: dull to vitreous; Crystal structure: crystalline/granular; Cleavage: none (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- tan, reddish-brown, and white with mottled iron staining
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: tan, reddish-brown, and white with mottled iron staining; Luster: dull to vitreous; Crystal structure: crystalline/granular; Cleavage: none (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, causing quartz grains to recrystallize. This specific specimen has been further shaped and smoothed by water erosion in a river or beach environment.
Uses & applications
Primarily used in construction as crushed stone, railway ballast, and decorative garden landscaping. High-purity quartzite is used in the glass and electronics industries.
Geological facts
Quartzite is one of the hardest and most durable common stones, often resisting weathering more effectively than the surrounding rock from which it originated. It is even harder than the steel of a pocket knife.
Field identification & locations
Identify in the field by its inability to be scratched by a steel blade and its granular, sugary appearance on a fresh break. It is a common find in glacial till, riverbeds, and along shorelines across North America and Europe.
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