igneous
Basalt with Quartz Veining
Basalt (SiO2-rich veins)
Hardness: 5-7 Mohs; Color: Dark grey/black with white/clear milky veins; Luster: Dull to vitreous; Structure: Fine-grained aphanitic matrix with crystalline quartz intrusions; Cleavage: None
- Hardness
- 5-7 Mohs
- Color
- Dark grey/black with white/clear milky veins
- Luster
- Dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 5-7 Mohs; Color: Dark grey/black with white/clear milky veins; Luster: Dull to vitreous; Structure: Fine-grained aphanitic matrix with crystalline quartz intrusions; Cleavage: None
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the surface. The quartz veins formed later when silica-rich hydrothermal fluids filled fractures in the cooling rock.
Uses & applications
Geological study, decorative landscaping, construction aggregate, and lapidary practice for beginners.
Geological facts
Basalt is the most common rock on Earth's surface, making up most of the ocean floor. The presence of quartz veins suggests a secondary geological event involving pressurized fluids.
Field identification & locations
Identified by its heavy weight and dark color contrasted with hard, translucent white bands. Commonly found in volcanic regions, riverbeds, and coastal areas near ancient tectonic activity.
