Stilbite crystals, a selection of specimens of this crystallized mineral species. Stilbite is a mineral, here many collector’s items presented with a description, one or more photos and sometimes a video. These stilbites are for sale. It is a silicate, subgroup of tectosilicate, a zeolite that is subdivided into two distinct species: stilbite-Ca, of chemical formula NaCa4(Si27Al9)O72-28(H2O) and stilbite-Na, both of monoclinic crystal system.