metamorphic
Banded Gneiss / Veined Metamorphic Pebble
Metamorphic Rock with Quartz/Feldspar Veins
Hardness around 6-7 on Mohs scale. Dark grey to black fine-grained host matrix contrastingly cross-cut by white quartz or feldspar veins. Dull to sub-vitreous luster, fine-grained to crystalline structure, well-rounded by stream or wave erosion.
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Physical properties
Hardness around 6-7 on Mohs scale. Dark grey to black fine-grained host matrix contrastingly cross-cut by white quartz or feldspar veins. Dull to sub-vitreous luster, fine-grained to crystalline structure, well-rounded by stream or wave erosion.
Formation & geological history
Formed deep within the Earth's crust under high temperature and pressure conditions through regional metamorphism. Hydrothermal fluids enriched in silica later intruded fractures, cooling to form the white quartz/feldspar veins. Later eroded and rounded by water transport.
Uses & applications
Primarily decorative in landscaping, aquariums, river rock beds, and as garden stones. Also collected as educational specimens for displaying metamorphic and veining structures.
Geological facts
The distinct white lines running through the dark rock are called hydrothermal veins. They act as a geological record of stress and cracking that occurred while the rock was buried deep underground.
Field identification & locations
Easily identified by contrast between a dark metamorphic host rock (like amphibolite or slate) and bright white intersecting quartz lines. Commonly found in glaciated riverbeds, beaches, and gravel deposits worldwide.
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