Mined from the purest of deposits from prehistoric freshwater lake-beds, diatomaceous earth consists of finely milled silica shells of ancient microscopic freshwater plants called diatoms. Of 600 deposits in the U.S., only 4 rate in purity by FDA standards to label as "Food Grade". We are proud to say our diatomaceous earth comes from a mine that meets all FDA requirements to make it a food grade product. Our purity and safety also meets and exceeds requirements set forth by our government. We also are proud to say that all of our manufacturing procedures are compliant and exceed FDA requirements.