metamorphic
Quartzite Pebble (Yellow/Cloudy Quartz)
Silicon Dioxide (SiO2) - Recrystallized Sandstone
Hardness: 7 on Mohs scale; Color: Pale yellow to off-white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Pale yellow to off-white
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Pale yellow to off-white; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the original sand grains to recrystallize and fuse together. The rounded shape is the result of water erosion in a beach or river environment.
Uses & applications
Used in construction as road ballast and aggregate. In cut form, it is used for decorative landscaping, jewelry (as 'river stones'), and in the manufacturing of glass and ceramics.
Geological facts
Quartzite is so hard and chemically resistant that it often survives intense weathering and erosion that destroys less durable rocks. It is frequently mistaken for chert or chalcedony, but it has a more granular internal texture.
Field identification & locations
Identify by its ability to scratch glass and its slightly translucent, sugary texture. Commonly found on beaches, riverbeds, and in glacial deposits globally. For collectors, look for smoothness and consistent color saturation.
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