Collection: Rhodonite

Often contains minor Mg and Fe. Structural studies and the recognition of new species in the rhodonite group indicate that the former simplified MnSiO₃ formula no longer represents the overall rhodonite group. A pure Mn-dominant rhodonite is better expressed as Mn²⁺Mn²⁺₃Mn²⁺[Si₅O₁₅], and indeed in 2019, this composition was recognized as the new rhodonite-group end-member vittinkiite.
The 5 cation sites M1-M5 exhibit ordering, which has given rise to such species as ferrorhodonite, which requires M5 to be Ca-dominant and M4 to be Fe²⁺-dominant.