igneous
Basalt with Quartz Vein
Mafic volcanic rock with hydrothermal SiO2 filling
Hardness: 6 (basalt) to 7 (quartz vein); Color: Dark grey to black matrix with a white/cream band; Luster: Dull/earthy matrix, vitreous vein; Structure: Fine-grained aphanitic matrix.
- Hardness
- 6 (basalt) to 7 (quartz vein)
- Color
- Dark grey to black matrix with a white/cream band
- Luster
- Dull/earthy matrix, vitreous vein
Identified More igneous →
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Physical properties
Hardness: 6 (basalt) to 7 (quartz vein); Color: Dark grey to black matrix with a white/cream band; Luster: Dull/earthy matrix, vitreous vein; Structure: Fine-grained aphanitic matrix.
Formation & geological history
The black basalt formed from rapid cooling of magnesium and iron-rich lava. The white vein was created later by hydrothermal fluids rich in silica flowing through a fracture and precipitating quartz.
Uses & applications
Primarily used as decorative garden stone, landscape rock, or as a geological teaching specimen.
Geological facts
The 'band' in the rock is a classic example of a cross-cutting relationship, where the vein is younger than the rock that contains it.
Field identification & locations
Identify by finding dark, heavy, fine-grained rocks with contrasting mineral lines; commonly found in volcanic regions, beaches, or riverbeds.
