Serpentinite
rock · common
Quick facts
- Formula
- — (mixture); serpentine ideal Mg3Si2O5(OH)4
- Hardness
- About 2.5–5 (varies with serpentine spec
- Luster
- Waxy to greasy; locally silky where chrysotile is present
- Colors
- Green to gray‑green, often mottled; may show lighter veins or dark magnetite specks
Serpentinite forms when ultramafic rocks such as peridotite hydrate at low temperatures, commonly in subduction and oceanic settings. It can host chrysotile (asbestos) veins and magnetite and is widely used as a decorative and carving stone.
Look for a slick, waxy feel, mottled green shades, and a soft-to-medium hardness that won’t scratch glass; weak magnetism and pale powder on filing also support serpentinite.
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