gypsum Search Term: gypsumSource Category: ASSISTGypsum is on the Recommended Chemicals list for Australian schools. Synonyms: calcium sulfate, dihydrate; calcium (II) sulphate dihydrate; sulfuric acid, calcium(II) salt, dihydrate; CAS Number: 10101-41-4; Signal Word: Warning. Tags: 10101-41-4calcium (II) sulphate dihydrate