igneous
Quartz Vein in Basalt
Silicon Dioxide (SiO2) in Mafic Igneous Rock
Quartz: Hardness 7, white to translucent, vitreous luster, hexagonal crystals. Matrix (Basalt/Diabase): Hardness 6, dark gray/green, fine-grained, dull luster.
Identified More igneous →
Explore Quartz Vein in Basalt in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Quartz: Hardness 7, white to translucent, vitreous luster, hexagonal crystals. Matrix (Basalt/Diabase): Hardness 6, dark gray/green, fine-grained, dull luster.
Formation & geological history
Formed when hydrothermal fluids rich in silica circulated through cracks and fissures in cooling volcanic rock (basalt) or hypabyssal rock (diabase). The quartz crystallized from these hot fluids over time.
Uses & applications
Primarily used for geological study or teaching specimens. Larger veins are mined for high-purity silica or gold, which often precipitates with quartz. Small samples are hobbyist items.
Geological facts
Quartz veins are often the most important indicators for gold prospectors, as gold is frequently found embedded within the quartz at the contact point with the host rock.
Field identification & locations
Identify by the sharp contrast between the white, hard crystalline quartz and the dark, fine-grained volcanic host rock. Commonly found in road cuts and mountain ranges with ancient volcanic activity.
