Marialite is a silicate mineral with a chemical formula of Na4Al3Si9O24Cl[5][6] if a pure endmember or Na4(AlSi3O8)3(Cl2,CO3,SO4) with increasing meionite content.

Crystals are usually prismatic with prominent forms of prisms and dipyramids.

Marialite was first described in 1866 for an occurrence in the Phlegrean Volcanic complex, Campania, Italy.

[4][5] Marialite occurs in regional and contact metamorphism: marble, calcareous gneiss, granulite and greenschist.

It also occurs in skarn, pegmatite and hydrothermally altered volcanic rocks.