Ancient Minerals Magnesium Bath Flakes are dry flakes of magnesium chloride hexahydrate and other trace minerals, in a convenient and economical form for utilization in baths and foot soaks. Ancient Minerals Magnesium Bath Flakes are approximately 47% magnesium chloride by weight. <p>Ancient Minerals Magnesium Bath Flakes are extracted from the Ancient Zechstein Seabed in Europe, 1600 to 2000 meters deep in the interior of the Earth. Well protected for the last 250 million years, they are the most pure magnesium flakes in the world and a mark of purity on every bottle of Ancient Minerals. <p>Ancient Minerals Magnesium Bath Flakes Ultra is a next generation formula incorporating the unique synergistic benefits of MSM magnesium. MSM (Methylsulfonylmethane) has long been revered as a superior form of sulfur supplementation, but as a topical it may facilitate more efficient uptake of magnesium ions. Ancient Minerals Magnesium Bath Flakes Ultra utilizes premium distilled OptiMSM, the world's purity standard for MSM.