Metamorphic
Quartzite River Pebbles
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale), Color: tan, white, and creamy yellow (often stained by iron), Luster: dull to vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: none (conchoidal fracture).
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Physical properties
Hardness: 7 (Mohs scale), Color: tan, white, and creamy yellow (often stained by iron), Luster: dull to vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: none (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. These individual specimens have been rounded and smoothed by fluvial (river) erosion over thousands of years.
Uses & applications
Used primarily for landscaping, decorative garden stones, and as 'kindness rocks' for painting. Historically used for road ballast and high-silica industrial manufacturing.
Geological facts
Quartzite is so hard that it will scratch glass and even steel. Water-worn pebbles like these are often found far from their original source, transported by ancient river systems.
Field identification & locations
Identify in the field by their extreme hardness, lack of visible grains (unlike sandstone), and smooth, rounded water-worn texture. Common in riverbeds and glacial deposits.
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