metamorphic
Serpentinite
Serpentinite (composed mainly of serpentine group minerals: (Mg,Fe)3Si2O5(OH)4)
AI-generated identification · may be incorrectHardness: 2.5 - 4.5 on Mohs scale; Color: Mottled deep reddish-brown to maroon mixed with dark olive-green and pale patches; Luster: Waxy to resinous, greasy feel when handled; Crystal structure: Monoclinic/Orthorhombic microcrystalline; Specific gravity: 2.5 - 2.8
- Hardness
- 2
- Luster
- Waxy to resinous, greasy feel when handled
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Physical properties
Hardness: 2.5 - 4.5 on Mohs scale; Color: Mottled deep reddish-brown to maroon mixed with dark olive-green and pale patches; Luster: Waxy to resinous, greasy feel when handled; Crystal structure: Monoclinic/Orthorhombic microcrystalline; Specific gravity: 2.5 - 2.8
Formation & geological history
Formed by hydrothermal metamorphism (serpentinization) of ultramafic igneous rocks like peridotite and dunite from the Earth's oceanic mantle, often at convergent plate boundaries or oceanic spreading ridges.
Uses & applications
Used primarily as decorative carvings, ornamental stones, polished collector eggs/spheres, architectural facing stone, and historically as a source of asbestos or industrial magnesium.
Geological facts
The rock gets its name from its mottled green, scaly appearance resembling snake skin. The red and brownish colorations seen in this specimen are often caused by oxidized iron (hematite/goethite) within the rock matrix. A paper label affixed vertically clearly reads 'Serpentine'.
Field identification & locations
Recognized in the field by its soapy or waxy feel, soft surface that can usually be scratched with a copper coin or pocketknife, and marbled patterns of green and reddish iron oxides. Common localities include California (where it is the state rock), Italy, Greece, Cornwall (UK), and New Zealand.
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