Industrially produced metakaolin may contain raw kaolin residues. Therefore, the aim of this work was to determine the impact of kaolin remains on the metakaolin and the final geopolymer quality. A series of mixtures based on metakaolin (Mefisto L05 by CLUZ Nove Straseci, Czech Republic) was prepared with the 0-60 wt% gradual addition of raw kaolin, and the mechanical strength of the final geopolymer products was tested. It was found that up to a 20 wt. % amount of kaolin in metakaolin does not weaken the geopolymer’s performance. Moreover, a geopolymer made of metakaolin with 2-4 wt% of kaolin showed slightly better mechanical properties than the geopolymers made from metakaolin itself.