igneous
Quartz-bearing feldspathic rock fragment
Likely granitic pegmatite or quartz–feldspar vein material; predominantly quartz (SiO₂) and feldspar
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray-white, with vitreous quartz luster and blocky, cleavable feldspar. The small angular fragment appears crystalline and lacks obvious layering or foliation.
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Physical properties
Hardness about 6–7 Mohs; pale gray-white, with vitreous quartz luster and blocky, cleavable feldspar. The small angular fragment appears crystalline and lacks obvious layering or foliation.
Formation & geological history
Likely formed by slow cooling of silica-rich magma or crystallization from a hydrothermal vein, generally in Precambrian to younger continental crust. Exact age and locality cannot be determined from the photograph.
Uses & applications
Common granitic material is used as aggregate, dimension stone, and landscaping rock; attractive quartz-rich pieces may be collected but this fragment has little gem value.
Geological facts
Quartz fractures conchoidally and does not show cleavage, whereas feldspar commonly breaks along two cleavage planes. The visible gray translucent area is probably quartz, with white feldspar along the edge.
Field identification & locations
Identify by its interlocking grains, pale color, glassy quartz, and harder-than-steel appearance; a knife may scratch feldspar but generally not quartz. Common worldwide in granite, pegmatite, and vein deposits.
