sedimentary
Ironstone Nodules (Limonite/Hematite)
Goethite/Hematite mix (FeO(OH)/Fe2O3)
Hardness: 5-5.5 on Mohs scale; Color: Dark brown to reddish-orange; Luster: Dull, earthy, or sub-metallic; Structure: Often concretionary or massive; Specific Gravity: 3.3-4.3.
- Hardness
- 5-5
- Color
- Dark brown to reddish-orange
- Luster
- Dull, earthy, or sub-metallic
Identified More sedimentary →
Explore Ironstone Nodules (Limonite/Hematite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-5.5 on Mohs scale; Color: Dark brown to reddish-orange; Luster: Dull, earthy, or sub-metallic; Structure: Often concretionary or massive; Specific Gravity: 3.3-4.3.
Formation & geological history
Formed by the precipitation of iron oxide minerals from groundwater within sedimentary rock layers, often around a nucleus like a leaf, shell, or pebble. Often dating from the Cretaceous to the Quaternary periods.
Uses & applications
Historically used as a low-grade iron ore; commonly used today in landscaping, as a decorative mineral for hobbyists, or as 'paint stones' due to their pigment quality.
Geological facts
These nodules are often mistaken for meteorites due to their heavy weight and dark, weathered 'fusion crust' look. Also known as 'Moqui marbles' in specific regions like Utah.
Field identification & locations
Identify in the field by their weight relative to size and a reddish-brown streak test on unglazed porcelain. Commonly found in eroded sandstone areas or stream beds.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary