metamorphic
Quartz vein in foliated metamorphic rock
Likely quartz-bearing schist or gneiss; visible crystal is quartz (SiO₂)
AI-generated identification · may be incorrectGray-brown, strongly foliated host with a translucent to smoky-gray quartz crystal/vein. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and hexagonal crystal structure; host minerals may include mica, feldspar, and chlorite.
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Physical properties
Gray-brown, strongly foliated host with a translucent to smoky-gray quartz crystal/vein. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and hexagonal crystal structure; host minerals may include mica, feldspar, and chlorite.
Formation & geological history
Formed when sedimentary or igneous rock was subjected to elevated pressure and temperature, producing foliation; silica-rich fluids later deposited quartz in a fracture. Exact age and locality cannot be determined from the photograph.
Uses & applications
Mostly collected as a geological specimen or used for teaching and lapidary display; quartz-rich metamorphic rock may occasionally serve as decorative stone.
Geological facts
The planar, layered texture is characteristic of metamorphic foliation, while the harder, glassier material cutting across it is likely quartz. A steel blade should not scratch quartz, but quartz can scratch ordinary glass.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachians, Alps, Canadian Shield, and Himalayas. Confirm with a hardness test, streak (white), and inspection for mica flakes and quartz crystal faces.
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