metamorphic
Quartzite River Rock
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: tan/beige with iron staining, Luster: dull to waxy (smooth), Crystal Structure: granoblastic, Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: tan/beige with iron staining, Luster: dull to waxy (smooth), Crystal Structure: granoblastic, Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, then rounded by fluvial erosion in a river environment.
Uses & applications
Used in landscaping, construction aggregate, road ballast, and as decorative garden stones.
Geological facts
Quartzite is so tough that it often survives intense mechanical weathering that breaks down other rocks; it is harder than a steel knife and will scratch glass easily.
Field identification & locations
Identify by its hardness (cannot be scratched by steel) and lack of reaction to acid. Commonly found in riverbeds, glacial tills, and mountainous metamorphic belts.
