igneous
Quartz Vein in Basalt
Silica-infilled basaltic host rock
Hardness of 7 for the quartz veins and 5-6 for the dark host rock; colors are predominantly black/dark grey with contrasting white or translucent quartz banding; vitreous to dull luster; cryptocrystalline to microcrystalline structure; specific gravity around 2.6 to 2.9.
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Physical properties
Hardness of 7 for the quartz veins and 5-6 for the dark host rock; colors are predominantly black/dark grey with contrasting white or translucent quartz banding; vitreous to dull luster; cryptocrystalline to microcrystalline structure; specific gravity around 2.6 to 2.9.
Formation & geological history
Formed through volcanic activity where basaltic lava cooled and solidified, followed by hydrothermal fluids depositing silica into fractures and fissures over millions of years.
Uses & applications
Mostly collected as geological specimens or polished for ornamental display pieces.
Geological facts
Quartz veins within dark volcanic rocks are common indicators of past hydrothermal activity and regional tectonic stress fracturing.
Field identification & locations
Easily identified in the field by striking white mineral veins cutting directly through dark, fine-grained volcanic matrices. Commonly found in regions with historic volcanic or hydrothermal activity.
