metamorphic
Quartzite (Milky Quartz pebble)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: White to off-white with yellow/orange iron staining. Luster: Vitreous to waxy. Structure: Macro-crystalline (granulated). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- White to off-white with yellow/orange iron staining
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale. Color: White to off-white with yellow/orange iron staining. Luster: Vitreous to waxy. Structure: Macro-crystalline (granulated). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone or through hydrothermal vein cooling. This specific specimen is likely a water-worn river pebble, shaped by erosion over thousands of years.
Uses & applications
Used as an abrasive, in glass manufacturing, as construction aggregate, or as landscaping 'river rock'. High-purity quartzite is also used in the production of silicon metal.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Specimens like this often get their yellow tint from limonite or hematite staining seeping into micro-fractures.
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 tills, and mountainous regions worldwide.
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