RocksdayArkose vs Granite
How to tell them apart
A sandstone with lots of pink feldspar, eroded quickly from nearby granite.
Photo: James St. John, CC BY 2.0
A coarse-grained rock that cooled slowly deep underground, made of quartz, feldspar and mica or hornblende.
Photo: The stone gate, CC BY-SA 4.0
Key differences
- Granite crystals interlock; arkose grains are cemented.
Side by side
| Property | Arkose | Granite |
|---|---|---|
| Type | Sedimentary rock | Igneous rock |
| Mohs hardness | 6–7 | 6–7 |
| Luster | Granular | Granular, sparkly |
| Colors | Pink, Red, Gray | Pink, Gray, White, Black |
| Crystal system / structure | Clastic, feldspar-rich sand | Coarse-grained (phaneritic) |
| Specific gravity | 2.5–2.7 | 2.63–2.75 |
| Found in | Uluru, Australia; Flatirons, Colorado | Sierra Nevada, California; Stone Mountain, Georgia |
Properties that are the same for both are grayed out.
How to identify arkose
- Pinkish sandstone with chunky feldspar grains.
- Angular grains of quartz and feldspar.
- Gritty texture.
Structure: Clastic, feldspar-rich sand
Full Arkose guide →How to identify granite
- Speckled with interlocking grains you can see without a lens.
- Glassy gray quartz plus pink or white blocky feldspar.
- Black specks of mica or hornblende.
- Hard, with no layering or banding.
Structure: Coarse-grained (phaneritic)
Full Granite guide →More comparisons
Could you tell them apart from a blurry close-up?
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