sedimentary

Quartz-rich sandstone (possibly quartzite)

Quartz sandstone; if recrystallized, quartzite composed mainly of SiO₂

AI-generated identification · may be incorrect

Pale tan-gray, dull to slightly sparkly, with a rough, granular surface and no obvious cleavage. Quartz has Mohs hardness 7; sandstone hardness varies with cementation, while quartzite is typically very hard and scratches glass.

Identified October 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed from quartz-rich sand compacted and cemented in a sedimentary basin; if the grains have fused through heat and pressure, it is metamorphic quartzite. The image alone cannot establish its age or distinguish these confidently.

Uses & applications

Sandstone is used as building stone and aggregate; quartzite is used for paving, countertops, and decorative stone. This rough specimen is mainly suitable for collecting.

Geological facts

Quartz-rich sandstone can transform into quartzite during metamorphism, preserving its original composition while developing interlocking quartz grains.

Field identification & locations

Look for visible sand-sized grains and grains that rub or crumble away to favor sandstone; a dense, interlocking texture and glass-scratching hardness favor quartzite. Both occur widely, but a close-up or hardness test is needed for a confident identification.