In geology, the hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces.
It is the last stage in the formation of sedimentary rock. Many minerals may act as cements; the most common is silica (generally quartz), but calcite and other carbonates also occur, as do iron oxides, barite, anhydrite, zeolites, and clay minerals.