Crystallite \Crys"tal*lite\ (kr?s"tal-l?t), n. [See {Crystal}.] (Min.) A minute mineral form like those common in glassy volcanic rocks and some slags, not having a definite crystalline outline and not referable to any mineral species, but marking the first step in the crystallization process. According to their form crystallites are called {trichites}, {belonites}, {globulites}, etc.