<human>:  I am interested in geology and I would like to learn more about metamorphic rocks. Can you give me a list of common facts about metamorphic rocks?
<bot>: 
1. Metamorphic rocks are formed when existing rocks are changed by extreme heat and pressure.
2. Metamorphic rocks have been changed from one type of rock to another.
3. Metamorphic rocks are usually more resistant to weathering and erosion than other rocks.
4. Common metamorphic rocks include marble, slate, schist, gneiss and quartzite.
5. Metamorphic rocks are typically denser and therefore heavier than other rocks.
6. Metamorphic rocks form as a result of plate tectonics and can reveal clues about the type of rocks that were originally in a certain area.
7. Metamorphic rocks sometimes contain mineral crystals that are much larger than those in the original rock.
8. Metamorphic rocks typically form in mountain belts due to Earth's internal heat, folding and faulting.
9. Metamorphic rocks may have an abstract pattern of bands or stripes due to their movement and transformation.
10. Metamorphic rocks are generally harder to identify than other types of rocks.