Manganoeudialyte is an moderately rare mineral of the eudialyte group, with formula Na<sub>14</sub>Ca<sub>6</sub>Mn<sub>3</sub>Zr<sub>3</sub>Si<sub>2</sub>[Si<sub>24</sub>O<sub>72</sub>(OH)<sub>2</sub>]Cl<sub>2</sub>÷4H<sub>2</sub>O. The formula given is one of the forms that can be given, based on the originally reported one, and shows dominance of silicon at both the M3 and M4 sites. As suggested by its name, it is the manganese-analogue of eudialyte.
Manganoeudialyte was discovered in khibinites of the Poços de Caldas massif, Brazil. Associated minerals are aegirine, analcime, astrophyllite, cancrinite, fluorite, lamprophyllite, nepheline, potassium feldspar, rinkite, sodalite, and titanite.
Impurities in manganoeudialyte include strontium, potassium, niobium, aluminium, fluorine, and minor hafnium, cerium, and lanthanum.