metamorphic
Yellow Quartzite (River Pebble)
Metamorphic Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Yellow to brownish-yellow due to iron oxide staining; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Yellow to brownish-yellow due to iron oxide staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Yellow to brownish-yellow due to iron oxide staining; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure. This specific specimen has been further shaped by fluvial (river) erosion, creating its smooth, rounded 'pebble' texture. Geological age can range from hundreds of millions to billions of years.
Uses & applications
Used primarily in landscaping (river rock), construction aggregate, road ballast, and occasionally as a tumbling stone for beginner lapidary hobbyists.
Geological facts
Quartzite is so hard and chemically resistant that it often survives deep into the weathering process, forming the 'skeleton' of mountain ranges. It is harder than the steel of a pocket knife.
Field identification & locations
Identify in the field by its hardness (it will scratch glass and metal) and its grainy, sandpaper-like texture beneath the smooth surface. Common in riverbeds and glacial deposits.
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