Polymorphism and optical, magnetic and thermal properties of the either phyllo- or inosilicate-analogous borosulfate Cu[B2(SO4)4]

Reaction of Cu2[(OH)2CO3], H3BO3 and oleum yields either inosilicate-analogous α-Cu[B2(SO4)4] or the new phyllosilicate-analogous β-Cu[B2(SO4)4], both subject to Jahn–Teller distortion; two polymorphs of Cu(HSO4)2 and Cu[S2O7] are also reported.