PHYLLITE
Phyllite
is a low- to intermediate-grade, foliated metamorphic rock. It forms by
the metamorphism of slate. Phyllite is typically light gray to dark gray
to blackish in color. It has a slightly
shiny luster in the light, with slightly wrinkled or crinkled foliation
planes. It is principally composed of microcrystalline mica.
Phyllite
(4.5 cm across)