metamorphic
Quartzite with Differential Weathering
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: tan to pinkish-gray, Luster: dull to vitreous, Texture: granular, non-foliated, Structure: interlocking crystalline quartz grains
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to pinkish-gray, Luster: dull to vitreous, Texture: granular, non-foliated, Structure: interlocking crystalline quartz grains
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone subjected to extreme heat and pressure. The surface 'ribbing' or grooves are caused by differential weathering, where softer mineral inclusions or fractures eroded faster than the surrounding hard quartz.
Uses & applications
Commonly used as crushed stone for construction, road ballast, or as a decorative landscaping stone due to its durability. High-purity quartzite is used in glassmaking.
Geological facts
Quartzite is so hard that it will scratch glass and even high-quality steel tools. 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 and lack of reaction to acid. It often appears 'sugary' on a fresh break. Common in mountainous regions where ancient sedimentary basins were uplifted.
