sedimentary

Banded River Stone (Greywacke or Siltstone subtype)

Sedimentary Banded Siltstone

Hardness: 6-7 (Mohs scale), Color: Brown, tan, and dark grey bands, Luster: Dull to matte (waxy when wet), Crystal Structure: Fine-grained clastic, Cleavage: None (conchoidal to irregular fracture), Specific Gravity: 2.6-2.7

Identified July 6, 2026More sedimentary →

Explore Banded River Stone (Greywacke or Siltstone subtype) in the encyclopedia →

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Physical properties

Formation & geological history

Formed from the lithification of clay and silt-sized particles deposited in layers over millions of years. This specific specimen has been rounded and polished naturally by water erosion in a river or beach environment.

Uses & applications

Mostly used for decorative landscaping, aquarium decor, and pocket stones for meditation. Larger deposits are used as construction aggregate or road base.

Geological facts

The distinct bands represent different cycles of sedimentation, where varying mineral compositions or grain sizes were deposited during different seasonal or geological events.

Field identification & locations

Identify in the field by its smooth, water-worn texture and visible parallel layering. It is commonly found in riverbeds, glacial tills, and coastal areas. Collectors look for high-contrast banding.

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