metamorphic
Quartzite Pebble
Quartzite (mostly SiO2)
Hardness: 7 (Mohs scale), Color: light grey to white with speckled texture, Luster: vitreous to dull if weathered, Crystal structure: granular/non-foliated, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: light grey to white with speckled texture, Luster: vitreous to dull if weathered, Crystal structure: granular/non-foliated, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together. This specific specimen has been further shaped into a round pebble by water erosion (alluvial or beach action).
Uses & applications
Primarily used as a durable construction material (crushed stone), decorative garden stones, and sometimes for high-silica industrial manufacturing. Smooth pebbles are popular in landscaping and lapidary hobbies.
Geological facts
Quartzite is so strong that it usually breaks through the quartz grains rather than along the boundaries between them, unlike its parent rock, sandstone. It is one of the most chemically resistant and physically durable rocks on Earth's surface.
Field identification & locations
Identify in the field by its hardness (it will easily scratch glass and steel) and lack of reaction to acid. Look for it in riverbeds, glacial tills, or high-energy beach environments.
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