metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: yellowish-tan; Luster: vitreous to dull; Crystal structure: hexagonal (cryptocrystalline); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- yellowish-tan
- Luster
- vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: yellowish-tan; Luster: vitreous to dull; Crystal structure: hexagonal (cryptocrystalline); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, often during mountain-building events. This specimen has been rounded by fluvial action (water erosion).
Uses & applications
Used in construction as aggregate, railroad ballast, and decorative landscaping stones. Highly pure quartzite is used to produce silica sand for glass making.
Geological facts
Quartzite is so tough that it often outlasts the mountain ranges from which it originated, forming resistant ridges. It is often confused with marble, but quartzite will not fizz in acid and is much harder.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sugary texture under a lens. Common in riverbeds and glacial deposits worldwide. Collectors look for unique colors or translucent qualities.
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