sedimentary
Quartz-veined Greywacke
Silicon dioxide (SiO2) in Lithic Sandstone
Hardness: 6-7 Mohs; Color: Grey, charcoal, and white; Luster: Dull to vitreous on vein; Texture: Grainy matrix with smooth crystalline vein.
- Hardness
- 6-7 Mohs
- Color
- Grey, charcoal, and white
- Luster
- Dull to vitreous on vein
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Physical properties
Hardness: 6-7 Mohs; Color: Grey, charcoal, and white; Luster: Dull to vitreous on vein; Texture: Grainy matrix with smooth crystalline vein.
Formation & geological history
Formed as a poorly sorted sandstone in deep marine environments (turbidite) during the Paleozoic or Mesozoic eras. The white band is a quartz vein formed later by hydrothermal fluids filling a fracture.
Uses & applications
Mainly used as crushed stone for road construction, fill material, and as waterworn decorative pebbles in landscaping.
Geological facts
The distinct white line is a 'healed' crack where silica-rich water flowed through the rock and crystallized into quartz over millions of years.
Field identification & locations
Identify by the contrast between a dark, grainy matrix and a hard, light-colored vein that resists weathering. Common in mountain ranges and coastal areas with tectonic history.
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