• Metamorphic rocks are formed by “changing” pre-existing igneous, sedimentary or other metamorphic rocks.
* Metamorphic processes involve changes caused by exposure to heat, pressure, and chemically-active fluids.
• Driving forces are increased heat and pressure as rocks are buried deep into the earth in association with mountain-building periods.
• They typically develop a fabric or texture that differentiates it from the original rock it formed from (called a protolith).
• Commonly found in ancient crustal rocks exposed in mountain ranges and in the core of continental landmasses.
Examples: quartzite, slate, marble, gneiss, schist, and serpentinite (the State Rock of California)