The most commonly used form of Ferrous Sulfate is Dried Heptahydrate because it is free-flowing, has consistent iron, sulfur, water and oxygen contents, and goes into solution rapidly. This material is produced when Moist Ferrous Sulfate Heptahydrate crystals are dried using QCs four independent gas fired rotary kilns, leaving a dried free-flowing granular product that is screened for uniformity. This product is available in 50 lb. bags, bulk bags, dump trucks, pneumatic trucks, rail hopper and rail boxcars.