In addition to mica-infused clay and Sculpey's Granitex clay, there are a handful of other clays with inclusions. For instance, Fimo Soft offers clay with metallic glitters added into the mix. Cernit's line includes a handful of "nature colors", which imitate the look of stone, and there is an imitation marble clay in Fimo Soft's collection, as well.
Clays with inclusions are sold in the same size units as regular clays and are cured at the same approximate temperatures.