RocksdayLimestone vs Marble
How to tell them apart
A rock made mostly of calcite, often from shells and skeletons of sea creatures. It dissolves to create caves.
Photo: Mike Davis, CC0
Limestone recrystallized by heat and pressure into a mosaic of interlocking calcite grains.
Photo: Zyance, CC BY-SA 2.5
Key differences
- Marble has sparkly, sugar-like interlocking crystals.
- Limestone is dull, not sparkly, and may contain fossils.
Side by side
| Property | Limestone | Marble |
|---|---|---|
| Type | Sedimentary rock | Metamorphic rock |
| Mohs hardness | 3–4 | 3–4 |
| Luster | Dull | Sugary sparkle |
| Colors | White, Gray, Brown | White, Gray, Pink, Green |
| Crystal system / structure | Varied, often fossiliferous | Interlocking crystals (non-foliated) |
| Specific gravity | 2.5–2.7 | 2.6–2.9 |
| Found in | Bedford, Indiana; Tura, Egypt | Carrara, Italy; Yule, Colorado |
Properties that are the same for both are grayed out.
How to identify limestone
- Fizzes in dilute acid.
- Gray to cream, often with shell fossils.
- A knife scratches it.
- Weathers into smooth, pitted surfaces.
Structure: Varied, often fossiliferous
Full Limestone guide →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 →More comparisons
Could you tell them apart from a blurry close-up?
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