Phyllite
Phyllite is a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation . 
<triplet> Phyllite <subj> metamorphic rock <obj> subclass of <triplet> foliated <subj> metamorphic rock <obj> facet of <triplet> slate <subj> metamorphic rock <obj> subclass of