igneous
Basalt with Quartz/Calcite Veins
Basalt with hydrothermal vein infill
Hardness: 6 (basalt matrix), Color: Dark grey to black with white/tan veins, Luster: Dull to earthy (matrix) / vitreous (veins), Crystal Structure: Aphanitic (fine-grained), Specific Gravity: 2.8–3.0
Identified More igneous →
Explore Basalt with Quartz/Calcite Veins in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 (basalt matrix), Color: Dark grey to black with white/tan veins, Luster: Dull to earthy (matrix) / vitreous (veins), Crystal Structure: Aphanitic (fine-grained), Specific Gravity: 2.8–3.0
Formation & geological history
Formed from rapid cooling of magnesium-rich and iron-rich lava. The veins formed later when mineral-rich hydrothermal fluids filled fractures in the solid rock, typically in volcanic terrains or oceanic crust.
Uses & applications
Commonly used in construction as crushed stone, road base, or railroad ballast. Decorative smooth specimens are used in landscaping or as pocket stones.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The light-colored lines are known as 'veins' and indicate the history of fluid movement through the rock.
Field identification & locations
Identify by its heavy weight, dark color, and fine texture. Look for it in areas of past volcanic activity or in riverbeds where it has been water-worn. This specimen shows typical 'river rock' rounding.
