Powder x-ray diffraction has been the most common method for rapid structural analysis and identification of crystalline ceramic raw materials. However, new structural ceramic raw materials often have linebroadened or featureless XRD patterns due to structural strain or small crystallite size. Characterization of various silicon carbide and silicon nitride powders and ceramic fibers by Si-29 NMR-MAS spectroscopy has revealed structural details and differences in these materials previously indistinguishable by XRD or other routine methods. Unique variables intrinsic to a given ceramic synthesis process are reflected in the NMR-MAS spectra of the resulting products.