igneous
Quartz Veined Basalt
Mafic Volcanic Rock with Microcrystalline Quartz (SiO2)
Hardness: 6-7 Mohs; Color: Dark grey to green matrix with white/cream veins; Luster: Dull/earthy for matrix, vitreous for veins; Structure: Fine-grained aphanitic matrix with hydrothermal vein filling.
- Hardness
- 6-7 Mohs
- Color
- Dark grey to green matrix with white/cream veins
- Luster
- Dull/earthy for matrix, vitreous for veins
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Dark grey to green matrix with white/cream veins; Luster: Dull/earthy for matrix, vitreous for veins; Structure: Fine-grained aphanitic matrix with hydrothermal vein filling.
Formation & geological history
Formed from cooling lava flows (basalt) that subsequently fractured. Hydrothermal fluids rich in silica circulated through these cracks, precipitating quartz and creating the white veins seen today.
Uses & applications
Used primarily in construction as crushed stone for road bases and concrete aggregate. Attractive specimens are used as garden rocks or educational samples.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floors. The veins in this specimen record the history of tectonic stress that cracked the rock long after it solidified.
Field identification & locations
Identified by the dark, heavy, fine-grained host rock contrasted against hard, white, non-reactive veins. Found globally in volcanic provinces and coastal regions.
