| Gismondine | |
| Category: | Zeolite minerals |
| Formula: | CaAl2Si2O8·4(H2O) |
| Dana: | 77.1.3.1 |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | P21/n |
Gismondine is a mineral with the chemical formula CaAl2Si2O8·4(H2O). It is a zeolite or hydrated alumino-silicate. It forms colorless, bipyramidal crystals of orthorhombic symmetry.
Gismondine was named for Italian mineralogist Carlo Giuseppe Gismondi (1762–1824). It has been found in Iceland, Ireland, and Italy.