RocksdayCalcite vs Chabazite
How to tell them apart
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
A zeolite whose rhombohedral crystals look almost like little cubes.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Hardness: Chabazite is clearly harder: Mohs 4–5 versus 3.
- Acid (vinegar or dilute HCl): Calcite fizzes; Chabazite doesn't.
Key differences
- Calcite fizzes in acid and cleaves perfectly.
Side by side
| Property | Calcite | Chabazite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3 | 4–5 |
| Luster | Vitreous | Vitreous |
| Streak | White | White |
| Colors | Clear, White, Orange, Yellow, Blue, Green | White, Orange, Pink, Clear |
| Crystal system | Trigonal | Trigonal |
| Specific gravity | 2.71 | 2.05–2.2 |
| Formula | CaCO₃ | (Ca,Na₂,K₂,Mg)Al₂Si₄O₁₂·6H₂O |
| Found in | Iceland; Chihuahua, Mexico | Nova Scotia; Oregon |
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 chabazite
- Nearly cubic crystals in basalt cavities.
- Clear to peach.
- Doesn't fizz in acid.
Crystal system: Trigonal
Full Chabazite guide →More comparisons
Could you tell them apart from a blurry close-up?
Play today's Rocksday