sedimentary
Sandstone concretion (Ironstone-stained)
Arenite with Limonite/Hematite staining (Silica-based with Iron Oxides)
Hardness: 6-7 (quartz component but crumbly cement); Color: Tan, brown, and ochre; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 (quartz component but crumbly cement)
- Color
- Tan, brown, and ochre
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (quartz component but crumbly cement); Color: Tan, brown, and ochre; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.2-2.8
Formation & geological history
Formed by the precipitation of mineral cement (often iron oxides or silica) within the spaces between sediment grains. This specimen shows significant iron oxide staining and weathering typical of riverbeds or arid environments.
Uses & applications
Primarily of interest to amateur collectors and geologists as educational specimens; higher-grade sandstone is used in construction and glassmaking.
Geological facts
Concretions often take on biological shapes through mechanical weathering, a phenomenon known as pareidolia. This specimen shows 'rinds' where iron-rich water has permeated the rock.
Field identification & locations
Identify by the grainy texture (feels like sandpaper) and the visible layers or 'rinds' of color. Commonly found in sedimentary basins and along eroding shorelines.
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