diatomaceous earth demand We are wanting diatomaceous earth from freshwater sources (at least 90% amorphous silica with less than 1% crystalline silica). Around 325 mesh. We do look at the diatom species and generally prefer the tube/barrel shaped ones, although the species of diatom is less important than the oil absorption capacity (note that the tube/barrel shaped frustules seem to impart higher oil absorption). The oil absorption test is one that we do (an in-house method), and we find that it's best examined by comparing samples (side by side comparison) because otherwise, there is room for interpretation. Obviously, we were hoping for a low price, otherwise, we will simply keep using our current supplier (they supply very high-quality diatomaceous earth).