Making a statue?

Building a dam?

Making a fireplace?

Solid foundations?

Storing water within it?

Storing oil or gas within it?

Showing that sedimentary rocks are made of lots of fragments?

Showing that igneous rocks have interlocking crystals?

Showing that metamorphic rocks often have aligned minerals?

Showing that some rocks contain traces of past life?

Sedimentary rocks ranging from coarse to fine?

The difference between igneous rocks that formed by slow cooling and fast-cooled igneous rocks?

Metamorphic rocks that don’t have aligned minerals?

The metamorphic rocks that show a sequence of increasing metamorphism from an initial mudstone sedimentary rock?