sedimentary
Sandstone Cobble with Iron Staining
Arenite with Limonite/Hematite staining
Hardness: 6-7 (on Mohs scale for quartz grains); Color: Orange-brown, reddish-tan; Luster: Dull, earthy; Crystal structure: Granular/clastic; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 (on Mohs scale for quartz grains)
- Color
- Orange-brown, reddish-tan
- Luster
- Dull, earthy
Identified More sedimentary →
Explore Sandstone Cobble with Iron Staining in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (on Mohs scale for quartz grains); Color: Orange-brown, reddish-tan; Luster: Dull, earthy; Crystal structure: Granular/clastic; Specific Gravity: 2.2-2.8
Formation & geological history
Formed from compressed sand grains cemented by silica or calcite, later weathered by water action causing a rounded shape (cobble). The orange color is due to iron oxide staining from exposure to oxygen and moisture.
Uses & applications
Primarily used in landscaping, road base, and construction. Small cobbles have little industrial value but are used for decorative gardens.
Geological facts
The orange hue is essentially 'rock rust,' where iron-bearing minerals within or on the rock have oxidized. Sandstone makes up about 20% of all sedimentary rocks on Earth.
Field identification & locations
Identify by its gritty, sandpaper-like texture and visible sand grains. These are commonly found in riverbeds, glacial till, and coastal areas. Collectors look for unique banding or patterns caused by the iron staining.
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