The density of water is 1 g/cm³. Here are the densities of some common rocks:
Granite: 2.7 g/cm³
Basalt: 2.9 g/cm³
Marble: 2.7 g/cm³
Sandstone: 2.2 g/cm³
Limestone: 2.7 g/cm³
As you can see, most rocks have higher density than water. This means that they will sink in water. However, there are some rocks that are less dense than water, such as pumice, which has a density of 0.5 g/cm³. These rocks will float in water.
