metamorphic
Serpentinite (serpentine-rich metamorphic rock)
Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite, brucite, and relict olivine/pyroxene
AI-generated identification · may be incorrectTypically green, yellow-brown, black, or mottled; waxy to greasy luster and massive texture. Mohs hardness is about 2.5–4, with poor cleavage and specific gravity roughly 2.5–2.7; this specimen’s iron-rich weathering gives it rusty brown and golden tones.
Identified More metamorphic →
Explore Serpentinite (serpentine-rich metamorphic rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically green, yellow-brown, black, or mottled; waxy to greasy luster and massive texture. Mohs hardness is about 2.5–4, with poor cleavage and specific gravity roughly 2.5–2.7; this specimen’s iron-rich weathering gives it rusty brown and golden tones.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along oceanic crust, subduction zones, and tectonic faults. Formation ages vary widely, from Precambrian to modern geological settings.
Uses & applications
Used as decorative and architectural stone, carving material, aggregate, and historically as a source of asbestos where chrysotile is present; attractive pieces are collected, but cutting or grinding should be avoided without testing.
Geological facts
Often displays a mottled “scaly” or veined appearance and may weakly attract a magnet because of magnetite. It is California’s state rock and commonly represents ancient oceanic mantle exposed on land.
Field identification & locations
Common in ophiolites and tectonic belts, including California, Italy, New Zealand, Canada, and the Appalachian region. Identify by its green-brown waxy appearance, low hardness, and association with dark ultramafic rocks.
More like this
