sedimentary

Weathered sandstone or siltstone

Clastic sedimentary rock, likely quartz-rich sandstone; exact mineralogy requires testing

AI-generated identification · may be incorrect

Tan-brown, fine to medium clastic texture with dull earthy luster and apparent layering/lamination. Likely hardness around 5–7 for individual quartz grains, but the rock is friable; no obvious cleavage or crystal faces. Specific gravity commonly about 2.2–2.7.

Identified August 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand- or silt-sized sediment was deposited, compacted, and cemented, probably in a marine, shoreline, or river environment. The specimen may be Paleozoic or Mesozoic, but age cannot be determined from the photograph. Around western Michigan, glacially transported sedimentary rocks are plausible.

Uses & applications

Common sandstone is used as building stone, aggregate, paving, and sometimes decorative stone; attractive pieces may be collected, but this specimen appears to have low commercial value.

Geological facts

The elongated lighter and darker bands suggest bedding or weathering along sedimentary layers. A streak or powdery surface can result from iron-oxide staining, which produces the tan-brown color.

Field identification & locations

Look for visible grains, bedding, and gritty texture; quartz-rich sandstone scratches glass, while softer siltstone may not. A hand lens, dilute hydrochloric acid test, and examination of a fresh broken surface would help distinguish sandstone from siltstone or iron-rich shale.