This specification covers unfabricated and fabricated forms of high purity hydrated calcium sulfate hemihydrate or dihydrate for surgical implants. The requirements of this specification apply to calcium sulfate combined with two molecules of water or two calcium sulfate molecules with one water mole but does not include calcium sulfate anhydrite and calcium sulfate forms that contain reinforcing phases, medicaments, biological agents, and other such additives. All covered materials should conform to the requirements for set time, compressive strength, and in vitro degradation.