metamorphic
Quartzite Pebble
Quartzite (predominantly Silicon Dioxide - SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan with a sugary texture; Luster: Vitreous (glassy) to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline/granoblastic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or tan with a sugary texture
- Luster
- Vitreous (glassy) to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or tan with a sugary texture; Luster: Vitreous (glassy) to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline/granoblastic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure compressed the original sand grains, causing them to recrystallize into a dense, interlocking mosaic of quartz. This specimen shows a smooth, rounded shape indicative of alluvial (water-worn) transport in a river or beach environment.
Uses & applications
Used as a high-quality building material, railway ballast, and in stone decorative landscaping. Due to its high silica content, it is often used in the production of silicon and ferrosilicon for industrial applications.
Geological facts
Quartzite is so hard that it can scratch steel and glass. It is one of the most durable and weather-resistant rocks on Earth, often forming the 'backbone' of mountain ranges as it resists erosion better than the surrounding rock types.
Field identification & locations
Identify in the field by its hardness (it cannot be scratched by a steel knife) and its grainy, 'sugary' appearance when viewed closely. Unlike limestone, it will not fizz when exposed to acid. Found globally in ancient mountain belts and riverbeds.
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