Diatomaceous Earth Diatomite has been used as a filter aid for nearly a century. The ore is a soft,friable siliceous mineral. It is composed of the skeletons of microscopic plants deposited on the bottoms of oceans and lakes after and during the Miocene Age, from 100,000 to 15,000,000 years ago. Under the microscope the particles of diatomite show up in a variety of forms: symmetrical figures resembling disks, rods, cylinders and snowflakes. It is this shape factor combined with the rigidity of the particles that makes diatomite such an excellent raw material for the production of superior filter aids. Diatomaceous Earth is an amorphous for of silica. Filter adis are processed at above 1500 F(800C). Both calcined and fluxcalcined diatomite filter aids are free of organic matter and are non-adsorptive.