metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: tan to light orange (due to iron oxidation), Luster: dull to vitreous, Crystal structure: microcrystalline, dense and tough, Cleavage: none, breaks through grains.
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to light orange (due to iron oxidation), Luster: dull to vitreous, Crystal structure: microcrystalline, dense and tough, Cleavage: none, breaks through grains.
Formation & geological history
Formed from the metamorphism of quartz sandstone under heat and pressure. This specimen shows signs of being water-worn or tumbled from a riverine environment.
Uses & applications
Used in construction as crushed stone for road gravel and railroad ballast, in the manufacture of glass and ceramics, and as a decorative stone.
Geological facts
Quartzite is one of the hardest and most chemically resistant rocks on the Earth's surface. It is often mistake for marble, but can be distinguished because quartzite will not react to acid and is much harder.
Field identification & locations
Identify in the field by its hardness (will scratch glass) and lack of reaction to vinegar. Commonly found in mountain ranges or as pebbles in riverbeds and glacial deposits.
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