Rocks come from a few main natural processes and can be broadly classified into three types based on their origins: igneous, sedimentary, and metamorphic.

• Igneous rocks form from the cooling and solidification of molten rock. Deep underground, molten rock called magma cools slowly to form intrusive igneous rocks (e.g., granite). When magma erupts to the surface as lava and cools rapidly, it forms extrusive igneous rocks (e.g., basalt).

• Sedimentary rocks are formed by the accumulation and compression of sediments like sand, pebbles, and organic material, often in layers, over long periods. These sediments are weathered and eroded fragments of other rocks transported by water, wind, or ice.

• Metamorphic rocks originate from preexisting rocks (igneous, sedimentary, or other metamorphic rocks) that have been altered by high heat, pressure, or chemically active fluids deep within the Earth, without melting. This process changes their physical or chemical properties to form new rock types like marble or slate.

Additionally, rocks are ultimately made from stardust—the dust and particles from exploding stars—that coalesced over billions of years to form planets, including Earth, which itself is a huge rock body formed from dust and small rocks that melted and solidified in space.

Thus, rocks come from processes involving molten rock solidifying, sediments compacting, and existing rocks changing under pressure and temperature—reflecting a dynamic cycle called the rock cycle.

This is the natural process by which the rocks we see today originated and continue to transform.