Rocks seen with a petrografic microscope

In this display case, visitors can see some of the most common rocks, such as granite, marble, clay, and so on, and information on the minerals of which they are composed. In the slides that are next to each rock, which are taken throught a petrographic microscope, one can see the fine details of these minerals.
The hardness and the chemical composition of the mineral that make up the rock generally determine what it will be used for, and that is why knowledge of the mineralogy of the rocks is so important.