Because it is less dense than the material around it.
Is granite less dense than water.
Unlike most substances water is denser as a liquid than as a solid.
Oil floats on water because it is heavier than the same volume of water less dense but a stone will drop to the bottom because it has a much higher density than its volume in water denser.
The densest sandstone can reach 2 6 g cm 3 and shale can be up to 2 7 g cm 3.
By the way density is defined as the weight per unit volume for example the density of water is very close to 1 gram per cubic centimeter.
And if you know your igneous petrology you will see that the more mafic rich in magnesium and iron a rock is the greater its density.
Sedimentary rocks and granite which are rich in quartz and feldspar tend to be less dense than volcanic rocks.
If the brick floats then it is less dense than water.
The resulting magma is less dense than material typically found at that depth so it rises like oil in salad dressing.
Even though mercury is a liquid at room temperature it too is denser than granite at a value of 13 6 g cm 3.
In these zones the input of water rich oceanic crust causes partial melting at the base of the crust about 25 to 30 miles below the earth s surface.
Note that the density of pure water is defined to be 1 gram per cubic centimeter or g ml.
Granite has a felsic composition and is more common in recent geologic time in contrast to earth s ultramafic ancient igneous history.
The lighter granite rocks can be less dense than some sedimentary rocks which are different from granite in that they form over time through sediments sticking together unlike granite which is formed through volcanic energy.
The chemical dissolution of minerals due to water.
Limestone and marble weather faster than granite because.
Also pure water is less dense than seawater so fresh water can float on top of salt water mixing at the interface.
If this doesn t convince your boyfriend then find a new one who is not as dense.
A consequence is that ice floats on water.
Felsic rocks are less dense than mafic and ultramafic rocks and thus they tend to escape subduction whereas basaltic or gabbroic rocks tend to sink into the mantle beneath the granitic rocks of the continental cratons.