RocksdayAndesite vs Dacite
How to tell them apart
An intermediate volcanic rock typical of explosive volcanoes above subduction zones.
Photo: Photographer: Siim Sepp, 2005, CC BY-SA 3.0
A light gray volcanic rock between andesite and rhyolite, typical of explosive lava domes.
Photo: ScoriaPumice, CC0
Key differences
- Andesite is darker with no quartz.
Side by side
| Property | Andesite | Dacite |
|---|---|---|
| Type | Igneous rock | Igneous rock |
| Mohs hardness | 6 | 6 |
| Luster | Dull | Dull |
| Colors | Gray | Gray, White, Pink |
| Crystal system / structure | Porphyritic (crystals in fine groundmass) | Porphyritic (crystals in fine groundmass) |
| Specific gravity | 2.5–2.8 | 2.4–2.7 |
| Found in | The Andes; Cascade Range, USA | Mount St. Helens, Washington; Lassen Peak, California |
Properties that are the same for both are grayed out.
How to identify andesite
- Medium gray.
- White feldspar crystals and dark specks scattered in a fine-grained base.
- Heavier than rhyolite, lighter than basalt.
- No visible quartz.
Structure: Porphyritic (crystals in fine groundmass)
Full Andesite guide →How to identify dacite
- Light to medium gray.
- Scattered white feldspar and dark hornblende crystals.
- Fine-grained base; may contain small quartz grains.
Structure: Porphyritic (crystals in fine groundmass)
Full Dacite guide →More comparisons
Could you tell them apart from a blurry close-up?
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