metamorphic
Yellow Quartzite (River Pebble)
Quartzite (SiO2)
Hardness: 7 (Mohs scale). Color: Honey yellow to cream. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) system but appearing granular. Specific Gravity: 2.6-2.7. Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs scale)
- Color
- Honey yellow to cream
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 (Mohs scale). Color: Honey yellow to cream. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) system but appearing granular. Specific Gravity: 2.6-2.7. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing the original quartz grains to recrystallize and fuse into a dense rock. The rounded shape indicates secondary transport and erosion in a river or coastal environment.
Uses & applications
Commonly used as decorative landscaping stone (river rock), construction aggregate, or tumbled for use in beginner rock collections and jewelry.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, ending up as high-standing ridges or rounded pebbles in riverbeds. It is much harder than marble, even though they can look similar.
Field identification & locations
Identify in the field by its hardness (it will easily scratch glass and stainless steel) and its grainy, sandpaper-like texture beneath a polished surface. Commonly found in riverbeds, glacial tills, and ancient mountain belts globally.
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