More than one-half of the deep-sea carbonates in the Red Sea are estimated to have been inorganically precipitated. Aragonite-cemented layers were formed during glacially lowered stands of sea level, when Red Sea waters were highly saline. Some magnesian calcite lithic fragments might represent inversion products of aragonite; others are believed to have been precipitated directly from normal Red Sea water. Chemical, mineralogical and petrographic similarities with lithic fragments suggest that the magnesian calcite portion of the Red Sea lutite was also inorganically precipitated. Similar inorganic carbonate precipitation probably occurred in the Mediterranean Sea, during glacially lowered sea level.