metamorphic
Yellow Quartzite (River Pebble)
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale); Color: Yellow to tan due to iron oxide staining; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Yellow to tan due to iron oxide staining
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 (Mohs scale); Color: Yellow to tan due to iron oxide staining; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically during mountain-building events. This specimen has been further shaped and smoothed by fluvial (river) erosion.
Uses & applications
Used in gravel for construction, as decorative stones in landscaping, and occasionally as a source for high-purity silica in industrial glass making.
Geological facts
Quartzite is so tough that it often breaks through the quartz grains rather than around them, unlike sandstone. The yellow hue is usually a result of limonite or goethite inclusions.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its smooth, water-worn texture. It is commonly found in riverbeds and glacial till throughout North America.
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