metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray with reddish/brown staining from iron oxide; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white to gray with reddish/brown staining from iron oxide; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none, conchoidal fracture.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, usually during mountain-building events. This specific specimen has been rounded by fluvial (water) erosion.
Uses & applications
Used in construction as crushed stone or ballast. High-purity quartzite is used to produce glass, silicon metal, and ferrosilicon.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth. It is so tough that it often outlasts the surrounding rock layers during erosion, forming ridges and peaks.
Field identification & locations
Identify by its ability to scratch glass and lack of reaction to acid. Commonly found in riverbeds, glacial tills, and mountainous regions. It is often confused with white marble, but marble is much softer.
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