igneous
Basalt with Quartz Vein
Mafic Volcanic Rock with SiO2 intrusion
Hardness: 6-7 (basalt), 7 (quartz). Color: Dark grey to black matrix with a milky white vein. Luster: Dull or earthy matrix, vitreous vein. Structure: Fine-grained aphanitic matrix.
- Hardness
- 6-7 (basalt), 7 (quartz)
- Color
- Dark grey to black matrix with a milky white vein
- Luster
- Dull or earthy matrix, vitreous vein
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Physical properties
Hardness: 6-7 (basalt), 7 (quartz). Color: Dark grey to black matrix with a milky white vein. Luster: Dull or earthy matrix, vitreous vein. Structure: Fine-grained aphanitic matrix.
Formation & geological history
Formed from rapid cooling of magnesium-rich and iron-rich lava. The white vein formed later via hydrothermal activity, where silica-rich fluids filled cracks in the cooling basalt and crystallized into quartz.
Uses & applications
Basalt is used heavily in construction (aggregate, road base). Veined specimens are popular for aquarium decor, landscaping, and educational rock collections.
Geological facts
Basalt is the most common rock in Earth's crust and makes up most of the ocean floor. Small quartz veins like this one are often footprints of ancient high-pressure water systems underground.
Field identification & locations
Identify by its heavy weight, dark color, and the presence of a distinct hard white line that cannot be scratched by a steel knife. Commonly found in volcanic regions and riverbeds.
