There are lots of types of rock and each type has different properties and uses. For example, some are strong and hard but others are soft and sandy. Some rocks are harder than others. For example ...

There are roughly dozens of shades of black, gray, brown, and green river rock to choose from, and they’re usually up to 3 inches in ... can consist of different types of rock.

There are over 5,000 known types of minerals. Just a few minerals make up most of the rocks we see, though: feldspars, amphiboles, quartz, olivine, garnet, micas, calcite, and pyroxenes.