RocksdayBlueschist vs Schist
How to tell them apart
A rare blue-gray rock formed at high pressure but low temperature in subduction zones.
Photo: Shannon Heinle, CC0
A shimmering metamorphic rock full of aligned mica flakes, often studded with garnets.
Photo: Michael C. Rygel, CC BY-SA 3.0
Key differences
- Ordinary schist is silvery or green.
Side by side
| Property | Blueschist | Schist |
|---|---|---|
| Type | Metamorphic rock | Metamorphic rock |
| Mohs hardness | 5–6 | 4–5 |
| Luster | Silky to dull | Glittery |
| Colors | Blue, Gray | Silver, Gray, Green |
| Crystal system / structure | Foliated, glaucophane-rich | Medium-grained, foliated |
| Specific gravity | 3–3.2 | 2.7–3 |
| Found in | Franciscan Complex, California; Syros, Greece | Manhattan, New York; Grand Canyon (Vishnu Schist) |
Properties that are the same for both are grayed out.
How to identify blueschist
- Lavender to blue-gray color.
- Foliated, sometimes with red garnets.
- Found in old subduction zones.
Structure: Foliated, glaucophane-rich
Full Blueschist guide →How to identify schist
- Glitters with visible mica.
- Wavy, flaky layers.
- Often contains red garnets or other crystals.
- Splits unevenly along layers.
Structure: Medium-grained, foliated
Full Schist guide →More comparisons
Could you tell them apart from a blurry close-up?
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