Lithogenic silica

Lithogenic silica (LSi) is silica (SiO2) derived from terrigenous rock (Igneous, metamorphic, and sedimentary), lithogenic sediments composed of the detritus of pre-existing rock, volcanic ejecta, extraterrestrial material, and minerals such silicate. Silica is the most abundant compound in the Earth's crust (59%) and the main component of almost every rock (>95%).

Lithogenic Silica in Marine Systems
LSi can either be accumulated "directly" in marine sediments as clastic particles or be transferred into dissolved silica (DSi) in the water column. Within living marine systems, DSi is the most important form of silica Forms of DSi, such as silicic acid (Si(OH)4), are utilized by silicoflagellates and radiolarians to create their mineral skeletons, and by diatoms to develop their frustules (external shells). These structures are vitally important, as they can protect, amplify light for photosynthesis, and even help keep these organisms afloat in the water column. DSi more readily forms from biogenic silica (BSi) than from LSi, as the latter is less soluble in water. However, LSi is still an important supply to the silica cycle, due to it being a primary supplier of silica to the water column.