metamorphic
Yellow Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Yellowish-tan to brownish-orange; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
- Hardness
- 7 on Mohs scale
- Color
- Yellowish-tan to brownish-orange
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 7 on Mohs scale; Color: Yellowish-tan to brownish-orange; Luster: Vitreous to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.63-2.65
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing recrystallization of quartz grains. These pebbles are often tumbled and rounded by alluvial (river) or glacial action.
Uses & applications
Used in landscaping, road construction aggregate, and as a durable material for pathways. Higher quality specimens are used for tumbling and jewelry as 'river stones'.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, ending up as rounded pebbles in riverbeds and on beaches. It is one of the most chemically and physically resistant rocks on Earth's surface.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its lack of visible grains compared to sandstone. Commonly found in riverbeds, glacial tills, and desert pavements.
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