metamorphic
Quartz-bearing sandstone or quartzite fragment
Likely quartzite with iron-oxide staining; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectWhite to translucent gray quartz forms a granular lower zone, while the reddish-brown portion is probably iron-stained quartz-rich rock. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and conchoidal fracture; the specimen appears dense and fine-grained.
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Physical properties
White to translucent gray quartz forms a granular lower zone, while the reddish-brown portion is probably iron-stained quartz-rich rock. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and conchoidal fracture; the specimen appears dense and fine-grained.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized during metamorphism, commonly during mountain-building; iron oxides produce the red-brown coloration. The exposed fragment cannot establish a geological age or confirm whether it is quartzite rather than cemented sandstone.
Uses & applications
Suitable mainly for collecting or educational use; quartzite is used as durable aggregate, dimension stone, countertops, and paving, while quartz may be used in glass and industrial applications.
Geological facts
The sharp boundary between white quartz-rich material and reddish matrix may also indicate a quartz vein cutting iron-stained host rock. A steel nail should not scratch quartz, while a knife may scratch softer sandstone matrix.
Field identification & locations
Common in metamorphic belts and quartz-vein settings worldwide, including the Appalachians, Rocky Mountains, and many Precambrian terrains. Test hardness, grain texture, and acid reaction; a vinegar test is generally negative for quartz-rich material.
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