Rocks can be classified into three major groups according to their?

Rocks can be classified into three major groups according to their origin and appearance. The three major groups of rocks are igneous, sedimentary, and metamorphic rocks. Igneous rocks are formed from cooled and solidified magma or lava. Sedimentary rocks are formed from the accumulation of sediment or organic matter that has been compacted and cemented together. Metamorphic rocks are formed from the transformation of pre-existing rocks due to heat, pressure, or chemical reactions. The appearance of a rock, such as its color and texture, can also provide clues about its origin and formation process. Therefore, the classification of rocks is based on both their origin and appearance.