Rocks can be hard, soft, permeable or impermeable, depending on what type of rock it is. Slate, marble, chalk and granite all have different uses.

Characteristics of rocks

Some rocks are harder than others. For example, granite is a very hard rock, but chalk is a very soft rock and wears away easily.

Some rocks, such as sandstone or chalk, let water soak through them. They are called permeable rocks.

Other rocks, such as marble and…