Metamorphic rock Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by texture and by chemical and mineral assemblage (metamorphic facies). They may be formed simply by being deep beneath
Heat Shield Rock This is essentially identical to the composition of a typical IAB iron meteorite found on Earth. The surface of the rock shows the "regmaglypts," or pits formed by the ablation of a meteorite during passage through the atmosphere, characteristic of meteorites. The largest dimension of the rock is nearing 31cm. No attempt was made to drill into the meteorite using the Rock Abrasion Tool (RAT), because testing on iron meteorites on Earth showed that the rover's drilling tools would be abraded and damaged. The RAT was designed to drill into ordinary rock, not into iron-nickel alloy. Meridiani Planum, the part