The high temperature titration of biogenic silica

A new method has been developed for measuring biogenic silica (amorphous) in marine sediments. It is based on the Högbom–Urey reactionCaCO3+SiO2 (biogenic silica)→CaSiO3 (wollastonite)+CO2.The reaction is carried out in evacuated sealed glass tubes with added excess reagent grade calcite at 500°C for 3 d. The product CO2 is measured in a calibrated manometer. The dependence of the reaction on time, temperature, product CO2 pressure, and other factors is examined.