Where is Iron-rich Sedimentary Rock found?
Hematitic Sandstone or Siltstone
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Open the appIron-rich Sedimentary Rock occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Iron-rich Sedimentary Rock
Colorado Plateau, USA
Extensive red bed sequences, including hematitic sandstones, are prominent in national parks like Zion, Bryce Canyon, and Grand Canyon, dating from the Permian to Jurassic periods.
Western Australia
While famous for Banded Iron Formations, some Proterozoic and Phanerozoic successions also contain significant hematitic sandstones and siltstones.
Devonian Old Red Sandstone, UK
A classic example of continental red beds, rich in iron oxides, found across parts of Scotland, Wales, and England.
Brazil
Various sedimentary basins contain iron-rich clastic rocks, particularly in regions with extensive iron ore deposits.
India
Sedimentary sequences associated with iron ore provinces often include hematitic sandstones and siltstones.
Collecting tips
- Look for Red Beds. Target geological formations known as 'red beds,' which are extensive sequences of red-colored sedimentary rocks, often indicative of arid or semi-arid continental depositional environments and the presence of iron oxides.
- Examine Outcrops. Look for distinctive reddish-brown to purplish-red outcrops in road cuts, river banks, cliffs, and quarries. The color is a primary indicator.
- Check for Hardness and Density. Hematite cement can make the rock harder and denser than typical sandstone or siltstone. Test with a steel knife (Mohs 5.5) to see if it scratches easily (if not, it's harder than 5.5).
- Perform a Streak Test. Rub a piece of the rock on an unglazed porcelain streak plate. A reddish-brown to cherry-red streak is characteristic of hematite, even if the rock itself appears darker.
- Observe Grain Size. Determine if the rock is primarily composed of sand-sized grains (gritty feel) or silt-sized grains (smooth but not plastic when wet). This distinguishes sandstone from siltstone.
Quick Check
- Color:
- Red, reddish-brown, purplish-red
- Luster:
- Dull to earthy
- Streak:
- Reddish-brown to cherry-red
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