However, there are some chemical differ.
ences between such xenocrysts and phenocrysts;
the latter are poor in NiO (0.40 to 0.28 and 0.33 to
0.l8Vo,r espectively)a nd rich in CaO (lesst han 0.15
and0 .23t o 0.15%0r,e spectively) when Fo contents
are the same .