According to my textbook, the anhydrous salt (CuSO4) is formed only by heating
to 250 C----this is not mild !!
Heating to 100 C gives the monohydrate (CuSO4.H2O)--is this "mild"
maybe.
I suspect that CuSO4.5H2O may be unaffected by really mild heating (30-50 C).
CoCl2.6H2O---look it up to learn about the inorganic chemistry of these salts
MgSO4.10H2O--look up the stable hydrate of MgSO4