What are some ways that people have utilized rocks?

There are lot of types of different rocks with each of them possessing certain unique qualities and properties. The people had learned over time that some of the rocks can be very useful to them, so they started using them.

The rocks are used as a construction material, for creating tools, machines, coins.

The rocks that have high metal content are heavily used by the people, especially the ones that have iron, nickel, silver, gold, aluminium, and they are used for the creating lot of tools, machines, coins.

Some, like the clay, bitumen, basalt, are used in the architecture for the building of the infrastructure in the human societies.  

the answer is blue river