RocksdayCalcite vs Carbonatite
The quickest way to tell Calcite from Carbonatite: Carbonatite is a rock — a mix of grains or minerals; Calcite is a single mineral.
One of the most common minerals on Earth and the main ingredient of limestone and marble. It breaks into perfect slanted boxes (rhombs) and fizzes in acid.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
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
Quick tests
- Texture: Carbonatite is a rock — a mix of grains or minerals; Calcite is a single mineral.
Key differences
- Calcite is the mineral; carbonatite is the rock, a mix of carbonates.
Side by side
| Property | Calcite | Carbonatite |
|---|---|---|
| Type | Mineral | Igneous rock |
| Mohs hardness | 3 | 3–4 |
| Luster | Vitreous | Sugary to earthy |
| Streak | White | — |
| Colors | Clear, White, Orange, Yellow, Blue, Green | White, Gray, Brown, Yellow |
| Crystal system / structure | Trigonal | Igneous carbonate, often coarse |
| Specific gravity | 2.71 | 2.7–3.1 |
| Formula | CaCO₃ | — |
| Found in | Iceland; Chihuahua, Mexico | Ol Doinyo Lengai, Tanzania; Mountain Pass, California |
Properties that are the same for both are grayed out.
How to identify calcite
- Fizzes in cold dilute hydrochloric acid (or slowly in vinegar).
- Breaks into rhomb-shaped pieces along three cleavage planes.
- Hardness 3 — a copper coin barely scratches it, a knife easily does.
- Clear pieces show double images of text underneath.
Crystal system: Trigonal
Full Calcite guide →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 →More comparisons
Frequently asked questions
What is the difference between calcite and carbonatite?
Calcite is a mineral (CaCO₃) with a Mohs hardness of 3 and a vitreous luster, usually colorless, white, orange, yellow, blue or green. 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.
How can you tell calcite from carbonatite?
Carbonatite is a rock — a mix of grains or minerals; Calcite is a single mineral. Calcite is the mineral; carbonatite is the rock, a mix of carbonates.
Could you tell them apart from a blurry close-up?
Play today's Rocksday