RocksdayCarbonatite vs Marble
To tell Carbonatite from Marble: Marble is metamorphosed limestone and is usually not full of rare-earth minerals.
An igneous rock made mostly of carbonate minerals. It fizzes like limestone, but it crystallized from magma.
Photo: Eurico Zimbres Zimbres, CC BY-SA 3.0
Limestone recrystallized by heat and pressure into a mosaic of interlocking calcite grains.
Photo: Zyance, CC BY-SA 2.5
Key differences
- Marble is metamorphosed limestone and is usually not full of rare-earth minerals.
Side by side
| Property | Carbonatite | Marble |
|---|---|---|
| Type | Igneous rock | Metamorphic rock |
| Mohs hardness | 3–4 | 3–4 |
| Luster | Sugary to earthy | Sugary sparkle |
| Colors | White, Gray, Brown, Yellow | White, Gray, Pink, Green |
| Crystal system / structure | Igneous carbonate, often coarse | Interlocking crystals (non-foliated) |
| Specific gravity | 2.7–3.1 | 2.6–2.9 |
| Found in | Ol Doinyo Lengai, Tanzania; Mountain Pass, California | Carrara, Italy; Yule, Colorado |
Properties that are the same for both are grayed out.
How to identify carbonatite
- Pale, and it fizzes in acid.
- A knife scratches it.
- Often with magnetite, mica or rare-earth minerals, and without fossils.
Structure: Igneous carbonate, often coarse
Full Carbonatite 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
Frequently asked questions
What is the difference between carbonatite and marble?
Carbonatite is an igneous rock with a Mohs hardness of about 3–4 and a sugary to earthy luster, usually white, gray, brown or yellow. Marble is a metamorphic rock with a Mohs hardness of about 3–4 and a sugary sparkle luster, usually white, gray, pink or green.
How can you tell carbonatite from marble?
Marble is metamorphosed limestone and is usually not full of rare-earth minerals.
Could you tell them apart from a blurry close-up?
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