igneous
Quartz-rich pegmatite or quartz vein rock
Mostly quartz (SiO₂), with probable feldspar and iron-oxide staining
AI-generated identification · may be incorrectWhite to gray, glassy-to-pearly quartz patches in a coarse, orange-brown matrix; hardness about 7 Mohs, no cleavage, conchoidal fracture, and vitreous luster. The orange coloration likely comes from limonite/goethite weathering, while the matrix may include feldspar or altered granite.
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Physical properties
White to gray, glassy-to-pearly quartz patches in a coarse, orange-brown matrix; hardness about 7 Mohs, no cleavage, conchoidal fracture, and vitreous luster. The orange coloration likely comes from limonite/goethite weathering, while the matrix may include feldspar or altered granite.
Formation & geological history
Likely formed from silica-rich hydrothermal fluids or a slowly cooled granitic pegmatite, probably during Precambrian to younger continental crust formation; exact age and origin require thin-section or chemical testing.
Uses & applications
Common material has little commercial value, but quartz-rich rock may be used as aggregate, ornamental stone, or a mineral-collecting specimen; gem value is unlikely unless clear crystals are present.
Geological facts
Quartz veins commonly cut granite, schist, and volcanic rocks, and iron staining can strongly color otherwise white quartz. Some similar specimens may contain feldspar, mica, or sulfide minerals.
Field identification & locations
Identify by testing hardness against glass, examining for glassy quartz grains, and checking whether the orange coating leaves a yellow-brown streak; a streak test and acid test help distinguish associated minerals. Common in granitic terrains and mineralized vein zones.
