metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: tan to light brown, Luster: vitreous to waxy, Crystal structure: trigonal (microcrystalline), Cleavage: none, Specific gravity: 2.63 - 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to light brown, Luster: vitreous to waxy, Crystal structure: trigonal (microcrystalline), Cleavage: none, Specific gravity: 2.63 - 2.65
Formation & geological history
Formed through the metamorphism of quartz sandstone under intense heat and pressure. This specimen is a water-worn river pebble, likely shaped over thousands of years by fluvial erosion.
Uses & applications
Used as an abrasive, in construction as crushed stone or ballast, and as a decorative stone in landscaping. High-purity quartzite is used to produce ferrosilicon and industrial silica.
Geological facts
Quartzite is so tough that it often breaks through the quartz grains rather than along their boundaries. It is one of the most durable rocks on the Earth's surface.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Commonly found in riverbeds, glacial tills, and mountainous metamorphic belts.
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