metamorphic
Weathered quartz-rich metamorphic rock, likely quartzite
Quartzite (mostly microcrystalline SiO₂), possibly iron-stained mica-bearing quartzite
AI-generated identification · may be incorrectHardness about 7 Mohs; tan, pink, gray, and brown coloration with glassy to dull luster, massive granular texture, and no obvious cleavage. The rusty tones reflect iron-oxide staining; pale reflective patches may be quartz or mica.
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Physical properties
Hardness about 7 Mohs; tan, pink, gray, and brown coloration with glassy to dull luster, massive granular texture, and no obvious cleavage. The rusty tones reflect iron-oxide staining; pale reflective patches may be quartz or mica.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under high heat and pressure, commonly during mountain-building; its exact geological age cannot be determined from the photograph. Surface weathering produced the rounded cobble form and iron staining.
Uses & applications
Used as crushed stone, road aggregate, building stone, countertops, landscaping rock, and occasionally as a lapidary material. This specimen is mainly of educational or decorative interest.
Geological facts
Quartzite commonly breaks across grains rather than around them and can be harder and more resistant than the original sandstone. The image does not show diagnostic features sufficient for a precise locality or subtype.
Field identification & locations
Look for a very hard, quartz-rich rock that scratches glass and shows fused grains; unlike sandstone, individual grains are not easily rubbed loose. Common in metamorphic mountain belts worldwide, including the Appalachians, Rockies, Alps, and Indian shield.
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