Answer:
On their mode of formation
Step-by-step explanation:
The classification of rocks into three major categories is strictly based on their mode of formation.
Rocks are naturally formed aggregates of minerals. Based on mode of formation, they can be classified into;
- Igneous rocks: these rocks are formed by the cooling and solidification of molten magma.
- Sedimentary rocks are formed by the compaction and lithification of sediment.
- Metamorphic rocks: these are changed rocks that have been formed by subjecting rocks to pressure and temperature conditions which causes an alteration of their minerology.