Sediments are transformed into sedimentary rock through cementation. This is a process that precipitates minerals in the spaces between sediment particles. As sediments are deposited, water moves through the pores between the grains. The water commonly contains dissolved silica (SiO₂) or calcium carbonate (CaCO₃). If the chemical conditions are right, quartz or calcite crystals will precipitate in the spaces between the sand grains. They will grow until the spaces are filled up and interlocking. The crystals cement the sediment together, creating solid rock.

Cemented gravel and pebbles form a sedimentary rock called conglomerate. Artificial cemented rocks (sand and gravel) is called concrete. Cemented sand forms sandstone and mud-sized particles make mudstone and siltstone. The type of cement also helps classify the sedimentary rock.

Conglomerate

Grains become cemented together