Blue Stone / Copper sulphate
Blue crystals or powder, usually shipped in multiwall paper sacks or drums, used in agriculture as a wood preservative and a cattle feed additive. Effloresces slowly on exposure to air. Is soluble in water, and if in contact with any volume of water, to the extent that it dissolves, will have a corrosive effect on other cargo, especially steel, steel drums, etc.
Crystals may cause damage to bags, with leakage and loss of weight. Copper sulphate should be kept well away form other cargo.