metamorphic

Weathered iron-rich quartzite or sandstone pebble

Ferruginous quartzite; primarily quartz (SiO₂) with iron-oxide coatings

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; tan to brown, dull earthy luster, granular texture, and no obvious cleavage. The rounded form and pitted surface indicate abrasion and weathering; exact identification requires a scratch and acid test.

Identified September 2, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely derived from quartz-rich sandstone that was compacted or weakly metamorphosed, with iron minerals oxidizing to limonite/goethite. Such pebbles commonly form in stream, glacial, or construction-fill deposits; age cannot be determined from the image.

Uses & applications

Usually collected as a commonplace field specimen or used as landscaping/gravel material; not typically suitable for jewelry unless it has unusual patterns or provenance.

Geological facts

The brown coloration is probably produced by hydrated iron oxides rather than the main rock-forming mineral. A quartz-rich specimen should scratch ordinary glass and show no fizz in dilute hydrochloric acid.

Field identification & locations

Common in stream gravels and weathered outcrops worldwide, especially regions containing quartzite or iron-rich sandstone. Confirm with a glass-scratch test, steel-file comparison, streak test, and inspection for visible quartz grains.