Wet chemical analyses of well-mixed fine drillings from a zirconium alloyed magnesium ingot showed that the resultant "soluble zirconium" was a function of the concentration of the hydrochloric or nitric acid that was used to digest the samples while the total zirconium could be readily and accurately determined. A solution containing 15 % of concentrated hydrochloric acid was used to determine the soluble zirconium. It was shown that insoluble zirconium that existed in the form of undissolved zirconium particles could play a positive role (similar to 30 %) in grain-refining magnesium and excellent grain refinement of magnesium alloys by zirconium depends on both soluble and insoluble zirconium in the melt immediately prior to pouring.