When mafic rocks are subducted along cold geotherms, they may pass through the
blueschist facies and ultimately into the eclogite facies. (a) What are the key minerals that will likely crystallise from mafic protoliths in each
of these facies? (Hint: two key minerals in each facies) (b) For each key mineral, state which broad silicate mineral group (e.g. feldspar group, garnet group, pyroxene group, etc.) it belongs to and give some information about its chemical composition and the silicate mineral structure group to which it belongs (e.g. isolated Si-O tetrahedral, single chain, double
chain etc).