Cations in Y ( M1 ) site are closely bound to 6 oxygens in octahedral coordination .
Pyroxene minerals are named according to the chemical species occupying the X ( or M2 ) site , the Y ( or M1 ) site , and the tetrahedral T site .
Cations in M1 ( M1 ) site are closely bound to 6 oxygens in octahedral coordination .
Pyroxene minerals are named according to the chemical species occupying the X ( or M2 ) site , the Y ( or M1 ) site , and the tetrahedral T site .