metamorphic
Quartzite (or Chert/Flint gravel)
Quartzite (SiO2 with iron oxide inclusions)
Hardness: 7 on Mohs scale; Color: tan, brownish, yellowish-white; Luster: dull to vitreous; Crystal structure: trigonal/microcrystalline; Cleavage: none, conchoidal fracture
- Hardness
- 7 on Mohs scale
- Color
- tan, brownish, yellowish-white
- Luster
- dull to vitreous
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: tan, brownish, yellowish-white; Luster: dull to vitreous; Crystal structure: trigonal/microcrystalline; Cleavage: none, conchoidal fracture
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or precipitation of microcrystalline quartz in sedimentary environments. Highly resistant to chemical and mechanical weathering.
Uses & applications
Commonly used as construction aggregate, road base, landscaping gravel, and decorative gravel.
Geological facts
Quartzite and chert are extremely durable and among the most common rock pebbles found in surface gravels worldwide due to their high resistance to erosion.
Field identification & locations
Can be identified by its hardness (scratches glass), waxy to sugary texture, and irregular conchoidal fracturing. Found in riverbeds, gravel pits, and soil overlays.
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