metamorphic
Quartzite River Rock
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: white to grey with iron staining; Luster: vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.63 - 2.65
- Hardness
- 7 on Mohs scale
- Color
- white to grey with iron staining
- Luster
- vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: white to grey with iron staining; Luster: vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.63 - 2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped by river erosion, rounding its edges over thousands of years.
Uses & applications
Used in railway ballast, construction aggregate, glass manufacturing, and as decorative landscape stone.
Geological facts
Quartzite is so tough it typically breaks through its constituent quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Identify by its hardness (will scratch glass easily) and its sugary texture under magnification. Found globally in riverbeds and mountainous regions. These are common collecting items for 'rock hounding' beginners.
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