A Western Australian fly ash has been analyzed by various techniques in order to quantify the reactive component that can be utilized in geopolymerization. Once the reactive amorphous aluminosilicate material was determined an estimate was made on how much material was left to act as filler material. Two approaches were used, the first a combination of XRD and XRF and the second an alkaline dissolution of fly ash. XRD/XRF results show that approximately 52 wt% of the fly ash is amorphous aluminosilicate material while the dissolution experiment provided a lower value of 39 wt%. Quantitative evaluation of minerals by scanning electron microscopy results showed an increase of iron oxide concentration in the undissolved component with increase in dissolution time leading to the conclusion that the amorphous iron does not participate in the geopolymerization process.