metamorphic
Gray Quartzite Pebble
Quartzite (chemically SiO2)
Hardness: 7 (Mohs scale), Color: light gray to bluish-gray, Luster: vitreous or dull when weathered, Structure: granoblastic (interlocking quartz grains), Specific Gravity: 2.6-2.7.
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Physical properties
Hardness: 7 (Mohs scale), Color: light gray to bluish-gray, Luster: vitreous or dull when weathered, Structure: granoblastic (interlocking quartz grains), Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further smoothed and rounded by water transport in a river or coastal environment.
Uses & applications
Used in construction as road ballast, in glass manufacturing if pure, as decorative stones in landscaping, and sometimes as 'worry stones' or for garden decor.
Geological facts
Quartzite is one of the most durable rocks on Earth; it is harder than steel and can easily scratch glass. This rounded shape, known as a 'river rock' or 'pebble,' indicates it has traveled miles from its source.
Field identification & locations
Identify by its hardness (will scratch glass) and its grainy, sandpaper-like texture that doesn't rub off. Commonly found along shorelines, stream beds, and glacial deposits.
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