This contribution presents a case examination of high-Mg andesite formation through magma mixing and its contribution to gold mineralization. The Axi high-Mg andesites from northwest China are host to a large epithermal gold deposit. They are porphyritic, with 15−40 vol% macrocrysts, primarily plagioclase (the dominant phase), along with clinopyroxene, amphibole, and quartz. Textural and compositional analyses of plagioclase macrocrysts reveal a variety of zoning types, including un-zoned, oscillatory-zoned, sieve-zoned, and patchy-zoned textures, often indicative of a multi-stage growth process. Compositions of the plagioclase macrocrysts vary significantly, with anorthite contents ranging from 10% to 78% for plagioclase, while some feldspars exhibit albite contents as high as 95%−99%. Clinopyroxene occurs either as macrocrysts or glomerocrysts, displaying both normal and reverse zoning patterns. Amphibole macrocrystals are found as opacitized grains or pseudomorphed by chloride, quartz, calcite, and Fe-Ti oxide. Quartz macrocrysts occasionally show corroded or embayed boundaries. The occurrence of alkali feldspar macrocrysts is limited, with some being replaced by plagioclase. Taken together, the sieve and patchy zoning in plagioclase, reverse zoning in clinopyroxene, and resorption of quartz macrocrysts suggest open-system processes, likely driven by mafic magma recharge within a silicic magma reservoir. The formation of high-Mg andesite through magma mixing is conducive to gold mineralization, as mafic magma recharge may introduce sulfur and gold into the system.