metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, beige, and white; Luster: Vitreous to dull; Crystal structure: Non-foliated granoblastic; Cleavage: None/conchoidal fracture; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Tan, beige, and white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, beige, and white; Luster: Vitreous to dull; Crystal structure: Non-foliated granoblastic; Cleavage: None/conchoidal fracture; Specific gravity: 2.6-2.7.
Formation & geological history
Formed via the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been rounded by fluvial or lacustrine water erosion.
Uses & applications
Used in construction as road ballast, railway ballast, and as a decorative stone in landscaping. High-purity quartzite is also used to produce silica sand for glassmaking.
Geological facts
Quartzite is so durable that it often survives intense weathering that destroys other rocks. It is frequently more resistant to erosion than the igneous rocks that might surround it.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in riverbeds, glacial deposits, and mountain ranges. Collectors look for unique banding or patterns.
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