Alluaivite

Alluaivite is an exceedingly rare mineral of the eudialyte group, with complex formula written as Na₁₉(Ca,Mn)₆(Ti,Nb)₃Si₂₆O₇₄Cl·2H₂O. It is unique among the eudialyte group as the only titanosilicate (other representatives of the group are usually zirconosilicates). References

1. https://en.wikipedia.org

2. https://en.wikipedia.org/wiki/Alluaivite

3. http://www.mindat.org/min-141.html