metamorphic
Brecciated quartzite (likely iron-stained quartz vein material)
Quartzite; predominantly quartz (SiO₂), with dark iron/manganese-oxide or mica-rich seams
AI-generated identification · may be incorrectWhite to gray, massive and granular with a strong vitreous-to-dull luster; Mohs hardness about 7, no obvious cleavage, and conchoidal-to-uneven fracture. The dark bands appear to be mineralized fractures or breccia seams rather than layering.
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Physical properties
White to gray, massive and granular with a strong vitreous-to-dull luster; Mohs hardness about 7, no obvious cleavage, and conchoidal-to-uneven fracture. The dark bands appear to be mineralized fractures or breccia seams rather than layering.
Formation & geological history
Formed when quartz-rich sandstone was intensely metamorphosed and recrystallized, with later fracturing and filling by dark oxides or other minerals. Such rocks commonly formed during ancient mountain-building events, often Precambrian to Paleozoic in age.
Uses & applications
Used as durable crushed stone, aggregate, landscaping rock, and occasionally as a decorative or lapidary material; generally not gem-grade.
Geological facts
Quartzite is harder and more resistant to weathering than its sandstone precursor, and fractured pieces may resemble breccia or quartz-vein material.
Field identification & locations
Identify it by its hardness—quartz should scratch glass—and by grains fused into a solid mass rather than separating like sandstone; dark seams may leave an earthy streak if oxide-rich. Common in metamorphic mountain belts worldwide.
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