metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: tan to light brown, Luster: dull to vitreous, Crystal Structure: non-foliated granoblastic, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: tan to light brown, Luster: dull to vitreous, Crystal Structure: non-foliated granoblastic, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been further shaped by river or glacial transport into a rounded pebble.
Uses & applications
Used as construction aggregate, railway ballast, landscaping stone, and in glass manufacturing if high purity. Smooth pebbles are often used in decorative gardening or as aquarium substrate.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks in weathering processes. It is often confused with marble, but unlike marble, it will not fizz when exposed to acid and is much harder than steel.
Field identification & locations
Identified in the field by its extreme hardness (cannot be scratched by a steel knife) and its grainy, sugary texture. Often found in riverbeds, beaches, or glacial till.
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