Eclogite is a dense, green plutonic rock composed
of coarse grains of green, sodium-rich pyroxene (omphacite)
and pale pink, magnesium rich garnet (almandite and
pyrope); kyanite and rutile are also common. Chemically,
an eclogite is equivalent to basalt. It occurs as small bodies
or blocks that appear to have been formed in the lowermost
crust and upper mantle, where igneous and metamorphic
processes merge. Most eclogites shows signs of retrogressive
metamorphism, with the pyroxene and garnet crystals
separated by rims of hornblende and plagioclase that have
developed from the reaction between these crystals.
Common minerals are: garnet, quartz, omphacite
pyroxene, and sometimes kyanite, phengite, paragonite,
zoisite, dolomite, and corundum.