sedimentary or mineral

Red Jasper or Ironstone concretion

SiO2 or Fe2O3

AI-generated identification · may be incorrect

Red to reddish-brown color, opaque, Mohs hardness 5.5-7 depending on composition, dull to somewhat earthy luster, compact and lumpy or nodular surface.

Identified July 24, 2026More sedimentary or mineral →

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Physical properties

Red to reddish-brown color, opaque, Mohs hardness 5.5-7 depending on composition, dull to somewhat earthy luster, compact and lumpy or nodular surface.

Formation & geological history

Formed through sedimentary processes, often as a concretion in sedimentary rocks or from silica-rich fluids precipitating in rock cavities. The red color is typically due to iron oxide inclusions.

Uses & applications

Commonly collected as river rocks or tumbling rough. Sometimes used for lapidary work if solid enough.

Geological facts

Red jasper and ironstone concretions are very common finds in dry riverbeds and desert environments.

Field identification & locations

Identify by its opaque red color, hardness (cannot be easily scratched by a steel nail if jasper), and irregular, somewhat rounded shape from weathering. Generally found worldwide.