sedimentary
Quartz Vein in Sandstone
Hydrothermal Quartz (SiO2) in Arenite
Hardness: 7 (quartz) vs 5.5-6 (sandstone base); Color: Milky white veins in tan/brown host rock; Luster: Vitreous to dull; Structure: Massive veins; Cleavage: None (conchoidal fracture on quartz).
- Hardness
- 7 (quartz) vs 5
- Color
- Milky white veins in tan/brown host rock
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (quartz) vs 5.5-6 (sandstone base); Color: Milky white veins in tan/brown host rock; Luster: Vitreous to dull; Structure: Massive veins; Cleavage: None (conchoidal fracture on quartz).
Formation & geological history
Formed when tectonic forces fractured a pre-existing host sandstone, followed by the injection of silica-rich hydrothermal fluids into the cracks. As the fluids cooled and pressure dropped, quartz crystals precipitated to fill the voids.
Uses & applications
Primarily used as decorative landscaping stones or garden rocks. High-quality quartz veins can sometimes be indicators for gold mineralization in certain geological provinces.
Geological facts
Quartz is one of the most chemically and physically resistant minerals. Even if the surrounding sandstone weathers away over millions of years, the durable quartz veins often remain as jagged ridges or pebbles.
Field identification & locations
Identify by looking for the 'sandwich' or 'veined' appearance where white crystalline material cuts across a granular host. Found globally in mountainous regions or areas with historical tectonic activity.
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