Type of rock that arise from the transformation of existing rock types, in a process called metamorphism.
The original rock (protolith) could be sedimentary, igneous, or existing metamorphic rock which is subjected to:
causing profound physical or chemical change.
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology + Petrophysics / Rock
[ Sedimentary Rock ] [ Igneous Rock ]