Stone is one of the most common natural materials on Earth, and its formation process has undergone millions of years of geological changes. It is formed by the long-term pressure and temperature action of rocks.

The formation of stone can be traced back to the interior of the Earth, specifically to the rock layers of the crust. In the crust, there are various types of rocks, such as granite, marble, sandstone, etc. These rocks are composed of different minerals and rock fragments.

When crustal plates move, rocks are subjected to tremendous pressure and temperature effects. During geological activities such as crustal plate collisions, volcanic eruptions, and earthquakes, rocks undergo changes. These changes include processes such as cooling and solidification of magma, metamorphism and recrystallization of rocks.

The cooling and solidification of magma is an important process in the formation of stone. When magma in the Earth's crust cools underground, its minerals gradually crystallize and form solid rocks. For example, granite is formed by the cooling of deep magma.

The metamorphism and recrystallization of rocks are also one of the key processes in the formation of stone. When rocks are affected by high pressure and high temperature, the minerals inside will rearrange and recombine, forming new rock structures and textures. For example, marble is formed by metamorphism of the original limestone.

In addition to the above process, there are other factors that can also affect the formation of stone, such as water erosion, weathering, etc. These natural forces, under long-term action, can alter the appearance and properties of rocks, gradually transforming them into stone that can be used for construction and decoration.

In summary, the formation of stone is a long and complex geological process that undergoes the effects of pressure, temperature, and geological activity. Through processes such as magma cooling and solidification, rock metamorphism and recrystallization, rocks are ultimately transformed into various types of stone for people to use and appreciate.