The main characteristics of magmatic rocks are: magma rising inside the crust invades the crust or ejects the surface and condenses, also known as igneous rocks. Magma mainly comes from the asthenosphere of the upper mantle, where the temperature is as high as 1300℃ and the pressure is about several thousand atmospheres, which makes magma have great activity and energy. According to its activity, it can be divided into extrusive rocks and intrusive rocks. Rock condensed by magma that does not reach the surface is called intrusive rock. The plutonic intrusive rocks have coarse grains. The particles of hypabyssal intrusive rocks are fine or uneven in size. Eruptive rocks are formed when magma is ejected from the surface, with low temperature and rapid cooling. They are usually glassy, semi-crystalline or cryptocrystalline texture with pores, streamline and other structures. Magmatic rocks are common, such as granite, widely distributed in the earth's crust, with medium-coarse grain structure and well-developed pore structure. Black dense basalt, rhyolite and rhyolite are acid extrusive rocks with obvious rhyolite structure.

Sedimentary rock: it is formed by weathering, transportation, deposition and consolidation of rocks formed on the ground under the action of external forces. Its main features are: ① obvious bedding structure; (2) Sedimentary rocks often contain ancient biological remains, which are fossilized due to fossilization; ③ Some of them have dry cracks, pores and nodules. Common sedimentary rocks include: gravels with a diameter greater than 3 mm, conglomerates cemented by round pebbles and other substances, sandstone cemented by sand grains with a diameter of 2mm ~ 0.05mm, shale composed of fine clay minerals, low-hardness limestone with calcite as the main component, etc.

The main characteristics of metamorphic rocks are as follows: ① Some have schist and other flaky structures; (2) Some are gneiss structures (not flaky), and banded or banded minerals, such as granite gneiss, are seen on the rock section; (3) Some are plate-like structures with extremely small particles, which are difficult to distinguish with naked eyes, such as slate. Common metamorphic rocks, such as marble recrystallized from calcite or dolomite, schist formed from shale and clay, schist formed from flaky and columnar rocks, gneiss formed from sedimentary rocks and magmatic rocks, quartzite formed from sandstone, etc.