metamorphic
Yellow Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: honey-yellow to tan; Luster: Vitreous to waxy; Structure: Granosblastic/Massive; Cleavage: None (conchoidal fracture); SG: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- honey-yellow to tan
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: honey-yellow to tan; Luster: Vitreous to waxy; Structure: Granosblastic/Massive; Cleavage: None (conchoidal fracture); SG: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, the quartz grains recrystallize and fuse together. The yellow staining is often caused by iron oxide (limonite) impurities.
Uses & applications
Used as crushed stone for road construction, ballasts, and decorative landscaping. High-quality smooth pieces are often used in lapidary for tumbling or as 'river rocks' in interior design.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock during erosion, frequently forming the tops of ridges and mountains. It is more resistant to weathering than granite.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of reaction to acid. It is commonly found in mountain belts where ancient sandstone beds have been subducted or compressed.
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