igneous
Quartz-Veined Porphyritic Basalt
Igneous rock with quartz vein (SiO2)
AI-generated identification · may be incorrectHardness 7 on Mohs scale for the quartz vein, 6 for the host rock. Color is dark grey-green with a contrasting white quartz band. Luster is vitreous on the vein and dull to sub-vitreous on the matrix.
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Physical properties
Hardness 7 on Mohs scale for the quartz vein, 6 for the host rock. Color is dark grey-green with a contrasting white quartz band. Luster is vitreous on the vein and dull to sub-vitreous on the matrix.
Formation & geological history
Formed from cooling volcanic basalt later fractured by tectonic activity and healed by hydrothermal fluids depositing silica, occurring over millions of years.
Uses & applications
Primarily collected as a geological specimen, sometimes tumbled or cut for ornamental lapidary use.
Geological facts
Quartz veins in volcanic rocks are natural hydrothermal mineral pathways often associated with precious metal deposits like gold.
Field identification & locations
Easily identified in the field by contrasting white silica bands cutting through a dark fine-grained volcanic matrix, commonly found in riverbeds and glacial drift.
