RocksdayRhodochrosite vs Siderite
How to tell them apart
A manganese carbonate in raspberry-red crystals or rose-and-white banded stalactites.
Photo: JJ Harrison (https://www.jjharrison.com.au/), CC BY-SA 4.0
An iron carbonate forming brown, often curved rhomb-shaped crystals.
Photo: DerHexer, Wikimedia Commons, CC BY-SA 4.0
Key differences
- Rhodochrosite is pink.
Side by side
| Property | Rhodochrosite | Siderite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3.5–4 | 3.5–4.5 |
| Luster | Vitreous | Vitreous to pearly |
| Streak | White | White |
| Colors | Pink, Red | Brown, Yellow, Gray |
| Crystal system | Trigonal | Trigonal |
| Specific gravity | 3.5–3.7 | 3.9–4 |
| Formula | MnCO₃ | FeCO₃ |
| Found in | Capillitas, Argentina; Sweet Home Mine, Colorado | Panasqueira, Portugal; Cornwall, England |
Properties that are the same for both are grayed out.
How to identify rhodochrosite
- Rose-pink to red, often banded.
- Rhomb-shaped crystals and cleavage.
- Fizzes in warm acid.
- Soft — a knife scratches it.
Crystal system: Trigonal
Full Rhodochrosite guide →How to identify siderite
- Tan to dark brown rhombs with curved faces.
- Fizzes in warm acid.
- Heavier than calcite.
Crystal system: Trigonal
Full Siderite guide →More comparisons
Could you tell them apart from a blurry close-up?
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