Metamorphic Rocks.
Metamorphic rocks are rocks that have changed their forms. When Earth's plates collide, the rock can be pushed down to the mantle. The crust has pockets of magma rising through it which provides heat which can produce metamorphic rocks. The high temperature and pressure much bigger than on Earth's surface, the rocks minerals can be changed into different minerals, so the rock is now a metamorphic rock.
Examples of Metamorphic Rocks
My first example of a metamorphic rock is quartzite. Quartzite was once a sandstone rock , but heat and pressure turned into a quartzite. Quatzite is a nonfoliated rock that is usually white or gray, but sometimes can be pink or red. It is very hard and is number 7 on the Moh's Hardness Scale. Here is a picture of quartzite.
A slate rock is a fine grained metamorphic rock. It was once shale,a sedimentary rock. It is thin and splits easily into parallel planes. Slate is a foliated rock and is usually gray,but sometimes is a light shade of green. . Here is a picture of slate.
Another example of a metamorphic rock is marble. Marble was once a limestone or dolomite rock. Marble has a uniform texture and is nonfoliated. When marble is in contact with any acid, it will fizz. Marble can come in many colors, including white,green,black,red,etc. Here is a picture of marble.
My last example is gneiss. Gneiss is a medium-coarse grained rock. It usually was once a shale rock. Gneiss is usually a color like black,white or gray. Here is a picture of Gneiss.
Metamorphic rocks are used for many things. Marble is used for decorating very often, as in counter tops, flooring, on window seals, etc. Schist can be used for paving or sculpture, and slate is often used as a roofing material.