RocksdayKimberlite vs Serpentinite
How to tell them apart
A rare volcanic rock from deep in the mantle — the main source of diamonds.
Photo: James St. John, CC BY 2.0
Rock of serpentine minerals, formed when mantle rock reacts with seawater. Slick, green and mottled.
Photo: Gabriel HM, CC BY-SA 4.0
Key differences
- Serpentinite is smoother and lacks rock fragments.
Side by side
| Property | Kimberlite | Serpentinite |
|---|---|---|
| Type | Igneous rock | Metamorphic rock |
| Mohs hardness | 4–6 | 3–5 |
| Luster | Dull | Waxy to greasy |
| Colors | Green, Gray, Blue, Yellow | Green, Black |
| Crystal system / structure | Volcanic breccia (ultramafic) | Massive, often sheared |
| Specific gravity | 2.8–3.2 | 2.5–2.8 |
| Found in | Kimberley, South Africa; Botswana | California Coast Ranges; Newfoundland |
Properties that are the same for both are grayed out.
How to identify kimberlite
- Blue-green to gray, often brecciated.
- Contains fragments of other rocks and mantle minerals.
- Weathers to crumbly 'yellow ground'.
Structure: Volcanic breccia (ultramafic)
Full Kimberlite guide →How to identify serpentinite
- Green to black with a waxy, slippery look.
- Polished, scaly surfaces where it was sheared.
- Softer than it looks.
Structure: Massive, often sheared
Full Serpentinite guide →More comparisons
Could you tell them apart from a blurry close-up?
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