RocksdayAplite vs Quartzite
How to tell them apart
A pale, fine-grained, sugary granite that fills thin dikes cutting through other granites.
Photo: Lysippos, CC BY-SA 3.0
Sandstone fused by metamorphism into an extremely hard rock of interlocked quartz grains.
Photo: Gabriel Haute Maurienne, CC BY-SA 4.0
Key differences
- Quartzite is almost all quartz and isn't in veins.
Side by side
| Property | Aplite | Quartzite |
|---|---|---|
| Type | Igneous rock | Metamorphic rock |
| Mohs hardness | 6–7 | 7 |
| Luster | Sugary | Sugary to glassy |
| Colors | White, Pink | White, Pink, Gray |
| Crystal system / structure | Fine-grained, sugary | Interlocking quartz grains (non-foliated) |
| Specific gravity | 2.6–2.7 | 2.6–2.7 |
| Found in | Sierra Nevada, California; Granite regions worldwide | Baraboo, Wisconsin; Sioux Falls, South Dakota |
Properties that are the same for both are grayed out.
How to identify aplite
- Thin white or pink veins with sharp edges.
- Fine, even, sugary grains.
- Very few dark minerals.
Structure: Fine-grained, sugary
Full Aplite guide →How to identify quartzite
- Breaks through the grains, not around them.
- Scratches glass.
- Smooth, sugary surface — not gritty.
- Doesn't fizz in acid.
Structure: Interlocking quartz grains (non-foliated)
Full Quartzite guide →More comparisons
Could you tell them apart from a blurry close-up?
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