Properties and characteristics of sodium silicate activated fly-ash-based geopolymers have been extensively investigated., but,the utilization of sodium aluminate activation has received little attention. The present works therefore, examines the properties of the starting materials and sodium aluminate solutions and their effect on the final material properties and microstructure of fly-ash-based geopolymers. To achieve this, starting sodium aluminate solutions were characterized with ATR-FTIR and Al-27 NMR spectroscopies to determine the coordination state of aluminum as a function of solution concentration and [OH]/[Al] ratio. Various fly-ash-based geopolymeric. matrixes were synthesized utilizing fly ash, kaolinite, K-feldspar, and slag as the mineral aluminum! sources. The,matrixes were activated with alkali silicate or alkali aluminate solutions as a function of pH, concentration, and alkali ion (Na+ or K+). FTIR and XRD studies combined with compressive strength tests demonstrated that in certain cases aluminate activated geopolymers were mechanically superior to traditional silicate activated geopolymers. Of specific interest was whether the superior properties could be related to a polysialate or calcium-aluminate-hydrate phase, which both contain 6-coordinate aluminum. A discussion of commercially viable industrial aluminate waste sources as potential large-scale feedstock for geopolymers was included.