What is a rock?
Properties and uses
Different types of rocks have different properties.
Some rocks are harder than others. For example, granite is a very hard rock. This makes it a good material for building as it doesn’t wear away easily.
Marble is another hard rock. It has an attractive texture and colour and it can be cut and polished. Because of this, it is used to make floor tiles and wall tiles. Some statues are made from marble too.
Chalk is a soft rock and wears away easily. This makes it ideal for making chalk sticks to write on blackboards.
Some rocks, such as sandstone or chalk, let water soak through them. They are called permeable rocks.
Other rocks, such as slate, do not let water soak through them. They are called impermeable rocks. Slate also splits easily into thin sheets. This makes it ideal for making roof tiles.