Major rock-forming minerals of the upper-mantle juvenile ultramafic
association are olivine, orthopyroxene, clinopyroxene, and
pyrope-almandine garnet, which at the transition zone are replaced
by majorite garnet, orthorhombic wadsleyite [β-(Mg,Fe)2SiO4], and
ringwoodite with a spinel-type structure [γ-(Mg,Fe)2SiO4]