Siliceous sediments are sedimentary deposits primarily composed of silica, often in the form of the mineral quartz. These sediments can originate from the weathering of rocks or the accumulation of microscopic organisms, such as diatoms and radiolarians, which have silica-based shells. They are commonly found in marine environments and can form thick layers on the ocean floor. These sediments play a crucial role in the geological record, providing insights into past environmental conditions. Over time, siliceous sediments can lithify, turning into silstone or chert, which are important rock types in geology.