metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Hardness: 2.5–6 on Mohs scale; Color: Greenish, blackish-green, or brownish; Luster: Waxy, greasy, or silky; Structure: Massive to fibrous; Cleavage: Poor; Specific Gravity: 2.5–2.6.
- Hardness
- 2
- Color
- Greenish, blackish-green, or brownish
- Luster
- Waxy, greasy, or silky
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Physical properties
Hardness: 2.5–6 on Mohs scale; Color: Greenish, blackish-green, or brownish; Luster: Waxy, greasy, or silky; Structure: Massive to fibrous; Cleavage: Poor; Specific Gravity: 2.5–2.6.
Formation & geological history
Formed through serpentinization, a low-temperature metamorphic process where ultramafic rocks (like peridotite) from the Earth's mantle are hydrated by water at tectonic boundaries.
Uses & applications
Used as decorative stone, in sculptures, as a source of magnesium, and historically as fire-resistant material. Some varieties are used in jewelry as 'New Zealand Jade'.
Geological facts
Serpentinite is the official state rock of California. It often contains magnetite, which can make specific specimens slightly magnetic.
Field identification & locations
Identify by its characteristic 'serpent-like' mottled green color and waxy feel. Commonly found in ophiolite complexes and mountain ranges like the Appalachians or the California Coast Ranges.
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