RocksdayMarble vs Skarn
How to tell them apart
Limestone recrystallized by heat and pressure into a mosaic of interlocking calcite grains.
Photo: Zyance, CC BY-SA 2.5
Colorful rock formed where hot fluids from magma react with limestone, often rich in ores.
Photo: Dexter Perkins, CC0
Quick tests
- Hardness: Skarn is clearly harder: Mohs 5–7 versus 3–4.
- Acid (vinegar or dilute HCl): Marble fizzes; Skarn doesn't.
Key differences
- Marble is mostly calcite.
Side by side
| Property | Marble | Skarn |
|---|---|---|
| Type | Metamorphic rock | Metamorphic rock |
| Mohs hardness | 3–4 | 5–7 |
| Luster | Sugary sparkle | Vitreous to granular |
| Colors | White, Gray, Pink, Green | Green, Brown, Red, White |
| Crystal system / structure | Interlocking crystals (non-foliated) | Coarse calc-silicate |
| Specific gravity | 2.6–2.9 | 3–3.5 |
| Found in | Carrara, Italy; Yule, Colorado | Sweden; Hunan, China |
Properties that are the same for both are grayed out.
How to identify marble
- Sparkly, sugary crystals on broken surfaces.
- Fizzes in acid.
- A knife scratches it.
- Often swirled or veined.
Structure: Interlocking crystals (non-foliated)
Full Marble guide →How to identify skarn
- Mix of garnet, green pyroxene and calcite.
- Heavy, coarse and colorful.
- Found at granite–limestone contacts.
Structure: Coarse calc-silicate
Full Skarn guide →More comparisons
Could you tell them apart from a blurry close-up?
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