igneous
Basalt with Quartz Vein
Basalt containing a microcrystalline quartz (SiO2) intrusion
Hardness: 6-7 Mohs; Color: dark grey to black matrix with white vein; Luster: dull to earthy matrix, vitreous vein; Crystal structure: aphanitic (fine-grained) matrix
- Hardness
- 6-7 Mohs
- Color
- dark grey to black matrix with white vein
- Luster
- dull to earthy matrix, vitreous vein
Identified More igneous →
Explore Basalt with Quartz Vein in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 Mohs; Color: dark grey to black matrix with white vein; Luster: dull to earthy matrix, vitreous vein; Crystal structure: aphanitic (fine-grained) matrix
Formation & geological history
Formed from rapid cooling of magnesium-rich and iron-rich lava. The white vein formed later as silica-rich hydrothermal fluids filled fractures in the cooling rock.
Uses & applications
Commonly used in construction as crushed stone for road base or railroad ballast; polished specimens can be used for decorative aquarium stones or pocket stones.
Geological facts
Basalt is the most common volcanic rock on Earth and also makes up much of the lunar surface (the dark patches or 'maria' seen on the moon).
Field identification & locations
Identified by its heavy weight relative to size, dark matte color, and characteristic quartz banding. Often found on beaches or in riverbeds where water has smoothed the edges.
