sedimentary
Hardpan Nodule / Ferruginous Sandstone
Ferruginous Sandstone (Fe-cemented sediment)
Hardness: 3-5 (varies by cementation); Color: Rusty brown, dull gray, or ochre; Luster: Dull or earthy; Structure: Granular with concretionary or pipe-like forms; Specific Gravity: 2.5-3.5.
- Hardness
- 3-5 (varies by cementation)
- Color
- Rusty brown, dull gray, or ochre
- Luster
- Dull or earthy
Identified More sedimentary →
Explore Hardpan Nodule / Ferruginous Sandstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3-5 (varies by cementation); Color: Rusty brown, dull gray, or ochre; Luster: Dull or earthy; Structure: Granular with concretionary or pipe-like forms; Specific Gravity: 2.5-3.5.
Formation & geological history
Formed by the precipitation of iron oxides (goethite/limonite) within sedimentary layers, typically in water-saturated environments or transition zones between soil layers. The specimen shows characteristic 'tube' formation often caused by mineralization around organic matter or water flow paths. Common in Quaternary deposits in the Baltic region.
Uses & applications
Generally used as a low-grade aggregate or for historical building stone in some regions. Primarily of interest as a geological curiosity for collectors.
Geological facts
These nodules are common in the Leningrad Oblast and surrounding Baltic areas, often found in glacial till or river banks. They are sometimes mistaken for meteorites or artifacts due to their unusual shapes and heavy iron content.
Field identification & locations
Check for a rusty or earthy streak (brown/yellowish). Look for the 'pipe' or hollow core structure. Found frequently in river beds or areas with high clay and iron-rich groundwater near Saint Petersburg.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary