Friday Rocks #35: Asbestos in Serpentinite and Blueschist

[caption id="attachment_541" align="aligncenter" width="610"]Asbestos in Serpentine and Blueschits Asbestos in Serpentinite and Blueschist[/caption]

The rock in this photo as three components. Serpentinite (Green-yellow in photo), blueschist (blue-grey in photo), and asbestos (white-green fibrous vein in photo). Blueschist forms through the metamorphism of basalt at high pressure and low temperature. Serpentinite is a metamorphic rock formed in a low pressure environment through a reaction between ultramafic rock from the Earth's mantle and water. The reaction is called "serpentiniztion" The asbestos mineral is often associated with serpentinite.

I found this rock when scrambling at the bottom of a cliff on the Big Sur coast of California. There were many small faults which sheared and mixed the different rocks types.

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