metamorphic
Quartzite (River Stone)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: White to translucent with yellow/orange iron staining, Luster: Vitreous to waxy (when wet), Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 – 2.7.
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Physical properties
Hardness: 7 (Mohs scale), Color: White to translucent with yellow/orange iron staining, Luster: Vitreous to waxy (when wet), Crystal structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 – 2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. This specific piece is a water-rounded cobble, likely eroded from a vein or bed and smoothed over thousands of years by river or glacial action.
Uses & applications
Commonly used in construction as aggregate, in landscaping, and high-purity quartzite is used in the glass and silicon industry. Tumbled pieces are used in home decor.
Geological facts
Quartzite is harder than steel and will easily scratch a glass plate. It is one of the most chemically and physically resistant rocks found on Earth's surface.
Field identification & locations
Identify in the field by its extreme hardness, lack of reactions to acid, and its sugary or crystalline texture on fresh breaks. It is found globally in mountainous regions and riverbeds.
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