Igneous
Basalt with Quartz Veins
Vesicular or aphanitic Basalt with SiO2 (Quartz) intrusions
Hardness: 6-7 (Mohs); Color: Dark grey or charcoal base with white/cream veins; Luster: Dull/earthy matrix with glassy veins; Structure: Microcrystalline; Specific Gravity: 2.8-3.0
- Hardness
- 6-7 (Mohs)
- Color
- Dark grey or charcoal base with white/cream veins
- Luster
- Dull/earthy matrix with glassy veins
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Mohs); Color: Dark grey or charcoal base with white/cream veins; Luster: Dull/earthy matrix with glassy veins; Structure: Microcrystalline; Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the surface. The white veins represent later hydrothermal activity where silica-rich fluids filled cooling cracks or fractures.
Uses & applications
Commonly used as decorative garden stones, in construction aggregate (road base), and as 'worry stones' or beach pebbles for collectors.
Geological facts
These are often called 'Wishing Stones' if a single white line encircles the entire rock. They are shaped into smooth ovals by tidal action and wave erosion over many years.
Field identification & locations
Identify by the high-contrast white crystalline lines cutting through a dark, fine-grained matrix. Often found on volcanic coastlines or in glacial till.
