metamorphic
Quartzite pebble
Quartzite (Silicon Dioxide: SiO2)
Hardness: 7 on Mohs scale; Color: Off-white to light gray; Luster: Vitreous to dull when unpolished; Texture: Granular but smooth due to river wear; Crystal Structure: Trigonal (microcrystalline)
- Hardness
- 7 on Mohs scale
- Color
- Off-white to light gray
- Luster
- Vitreous to dull when unpolished
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white to light gray; Luster: Vitreous to dull when unpolished; Texture: Granular but smooth due to river wear; Crystal Structure: Trigonal (microcrystalline)
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone subjected to extreme heat and pressure, typically during mountain-building events. This specimen has been further shaped by water erosion as river or beach gravel.
Uses & applications
Used extensively in road construction as railroad ballast, in the flooring industry, and crushed as decorative ground cover in landscaping.
Geological facts
Quartzite is so hard that it can scratch glass and steel. It is one of the most durable rocks found on the Earth's surface and often remains behind as pebbles after softer rocks have eroded away.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid. Commonly found in riverbeds, glacial deposits, and mountain outcrops worldwide.
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