Blueschist

About it

Blue to lavender-grey rock coloured by glaucophane, formed at high pressure but low temperature in subduction zones. Found in the Franciscan Complex of California and on the Greek island of Syros.

Type

Rock (metamorphic)

Group

Metamorphic (high-pressure)

Colours

blue, blue-grey, lavender, dark blue

Transparency

opaque

Typical values: real specimens vary. For more, see mindat.org.