Generally: W_0-1X₂Y₅Z₈O₂₂(OH, F, Cl)₂

W: 12-fold coordination - ions can't fit (A1 site) Na⁺, Ca²⁺ - coordination with OH^- in some cases

X: 6-8 fold site (M4 site)
Ca²⁺, Na⁺, Mn²⁺, Fe²⁺, Mg²⁺, Li⁺

Y: M1, M2, M3 possibilites - 6CN - only slightly distorted
Mg²⁺, Fe²⁺, Fe³⁺, Al³⁺, Ti⁴⁺ (only Ca can't fit here)

• M1 & M3 - oxygens and OH^- - 4 oxygens plus 2 OH^- or F^-
• M2 - normal octahedral, 6 oxygens

Z: typical tetrahedral - 4-fold
usually Si⁴²⁺, Al³⁺ - rarely anything else