glaucophane-schist facies . The facies (set of metamorphic mineral assemblages) in which mafic rocks are represented by combinations of sodic amphibole (e.g., glaucophane, crossite), lawsonite, sodic pyroxene, aragonite, epidote, and garnet. The mineral pair jadeite + quartz is also diagnostic. Exact definitions of the facies and its subdivisions vary (Turner, 1968). It represents lower temperatures and higher pressures than the greenschist facies. It is characteristic of metamorphism in subduction zones, with their unusually low geothermal gradients. Syn: blueschist facies.