igneous
Basalt with Quartz Veins
Amygdaloidal Basalt (matrix) with Crystalline SiO2 (veins)
Hardness: 6-7 (Mohs); Color: Dark grey to charcoal matrix with white/off-white banding; Luster: Dull/Earthy matrix with Vitreous veins; Structure: Fine-grained/Aphanitic igneous rock with secondary vein filling; Specific Gravity: 2.8 - 3.0
- Hardness
- 6-7 (Mohs)
- Color
- Dark grey to charcoal matrix with white/off-white banding
- Luster
- Dull/Earthy matrix with Vitreous veins
Identified More igneous →
Explore Basalt with Quartz Veins 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 charcoal matrix with white/off-white banding; Luster: Dull/Earthy matrix with Vitreous veins; Structure: Fine-grained/Aphanitic igneous rock with secondary vein filling; Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed through the rapid cooling of basaltic lava at the Earth's surface. The veins were created much later when hydrothermal fluids rich in silica circulated through cracks and fractures in the cooling rock, precipitating quartz.
Uses & applications
Common basalt is used extensively in construction as aggregate, road base, and railroad ballast. This specific water-worn specimen is a 'river rock' often used in landscaping or as a basic pocket stone for beginning collectors.
Geological facts
The dark 'stripes' or veins in rocks like this are often referred to as 'wishing stones' in folklore, especially if the white line forms a continuous circle around the stone. Basalt is the most common rock type in the Earth's crust, making up most of the ocean floor.
Field identification & locations
Identify in the field by looking for heavy, dark, fine-grained rocks with contrasting white lines. Commonly found in riverbeds, glacial tills, and along coastlines where volcanic activity once occurred. They are excellent for tumbling to show the contrast between the dark host rock and light veins.
