metamorphic
Quartzite Pebble
Quartzite (SiO2-dominant rock)
Hardness: 7 on Mohs scale; Color: Tan, brown, or yellowish-orange due to iron staining; Luster: Vitreous to dull/waxy; Structure: Granoblastic-polygonal (interlocking quartz grains); Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or yellowish-orange due to iron staining
- Luster
- Vitreous to dull/waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or yellowish-orange due to iron staining; Luster: Vitreous to dull/waxy; Structure: Granoblastic-polygonal (interlocking quartz grains); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed when quartz-rich sandstone is subjected to intense heat and pressure (metamorphism). This specific specimen has been further shaped by fluvial or glacial transport, rounding its edges over thousands of years into a 'river pebble.'
Uses & applications
Commonly used as construction aggregate, ballast, and in decorative landscaping. High-purity quartzite is used to produce silicon for electronics and glass.
Geological facts
Quartzite is one of the hardest and most durable common rocks. It is so tough that it often survives erosion that destroys other rocks, which is why it is frequently found as rounded stream pebbles even far from its source.
Field identification & locations
Field identification involves its ability to scratch glass easily and the way it breaks through quartz grains rather than around them (unlike sandstone). It is found globally in mountainous regions and riverbeds.
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