metamorphic
Weathered quartz-rich metamorphic rock
Likely quartzite or quartz-mica schist; predominantly SiO₂ quartz with iron-oxide staining
AI-generated identification · may be incorrectHardness about 6.5–7 for quartz; white to gray with rusty yellow-brown limonite/hematite patches, vitreous to dull luster, and an interlocking granular texture. Visible foliation or banding is weak, suggesting quartzite rather than strongly schistose rock.
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Physical properties
Hardness about 6.5–7 for quartz; white to gray with rusty yellow-brown limonite/hematite patches, vitreous to dull luster, and an interlocking granular texture. Visible foliation or banding is weak, suggesting quartzite rather than strongly schistose rock.
Formation & geological history
Formed when quartz-rich sandstone was metamorphosed under elevated temperature and pressure, commonly during mountain-building; the exact geologic age cannot be determined from the image. Brown coloration results from later weathering and oxidation of iron-bearing minerals.
Uses & applications
Used as durable aggregate, road stone, riprap, building stone, and occasionally decorative slab material; generally lacks gemstone value.
Geological facts
Quartzite is notably resistant to weathering and commonly forms ridges or resistant landscape outcrops. Iron staining can superficially resemble gold but is typically earthy and nonmetallic.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachians, Rocky Mountains, Alps, and Precambrian shields. A glassy quartz-rich surface, great hardness, and inability to scratch quartz distinguish it from softer sandstone; acid produces no reaction.
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