The nitriding of compacted silicon powder shapes to give reaction-bonded components (RBAN), their more recent densification by post-preparative methods (SRBSN), and the liquid-phase densification of silicon nitride powder by hot-pressing (HPSN) were all innovative at the time of their discovery but have since had only limited success. The goal from the earliest days of silicon nitride technology has been the ceramic gas turbine, and there is still no commercial process for producing complex shapes to engineering tolerances with the required combination of properties. One approach to the problem is by ceramic alloying and, to illustrate the nature of innovation through its various stages, the development of Sialons is described. Silicon nitrides have silicate structures to which simple principles of silicate chemistry can be applied. This has provided new vitreous and crystalline materials, some of which seem suitable for engine applications.