Calderite - Mineral in-between Spessartine and Andradite, so that its formula is (Mn,Ca)₃(Fe³⁺,Al)₂Si₃O₁₂.
(Formula of Spessartine = Mn₃Al₂Si₃O₁₂)
(Formula of Andradite = Ca₃Fe³⁺₂Si₃O₁₂)

Other combinations for this mineral exist, so that it may be a separate mineral with the formula Mn₃Fe³⁺₂Si₃O₁₂.
Calderite is a member of the Garnet Group.