RocksdayIronstone vs Sandstone
How to tell them apart
Sedimentary rock rich in iron minerals such as siderite, goethite or hematite.
Photo: James St. John, CC BY-SA 4.0
Sand grains — mostly quartz — cemented together. Many sandstones preserve ancient beaches, rivers or desert dunes.
Photo: Unknown, Public domain
Quick tests
- Hardness: Sandstone is clearly harder: Mohs 6–7 versus 4–6.
- Heft: Ironstone feels noticeably heavier for its size (specific gravity 3–3.6 vs 2.2–2.8).
Key differences
- Red sandstone is lighter and gritty.
Side by side
| Property | Ironstone | Sandstone |
|---|---|---|
| Type | Sedimentary rock | Sedimentary rock |
| Mohs hardness | 4–6 | 6–7 |
| Luster | Dull | Dull, gritty |
| Colors | Brown, Red, Orange | Brown, Red, Yellow, White, Orange |
| Crystal system / structure | Iron-rich sedimentary | Clastic, sand-sized grains |
| Specific gravity | 3–3.6 | 2.2–2.8 |
| Found in | Cleveland Hills, England; Birmingham, Alabama | Zion and Arches, Utah; Petra, Jordan |
Properties that are the same for both are grayed out.
How to identify ironstone
- Heavy, rusty brown to red.
- Often forms nodules or layers in shale.
- Rusty-brown streak.
Structure: Iron-rich sedimentary
Full Ironstone guide →How to identify sandstone
- Gritty, like sandpaper.
- Individual sand grains visible with a lens.
- Grains rub off when scraped.
- Often layered or cross-bedded.
Structure: Clastic, sand-sized grains
Full Sandstone guide →More comparisons
Could you tell them apart from a blurry close-up?
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