They are the most useful. Slate is made to make your stairs on the outside.
Marble is used for sculptures, and coal is used for fuel and energy like light.
The most useful ones are marble, coal and slate. Look below and you will see them. You will see quartz everywhere. S pecial rocks like valuable crystal is made from igneous volcanic rock. Igneous rock is made out of lava that shoots out of a volcano or earthquakes and turns into an igneous rock.