High Au concentrations (4-25 ppb) in titanomagnetite concentrates from basalts and basaltic andesites of the Izu-Oshima and Fuji volcanic areas in the East Japan are indicate that Au is strongly partitioned into titanomagnetite relative to the bulk rock. The concentration of Au in volcanic rocks increases during the early stages of fractional crystallization, dominated by olivine, pyroxenes, and plagioclase, but decreases with subsequent fractional crystallization involving titanomagnetite. A delay in titanomagnetite formation during fractional crystallization subsequently results in comparatively high concentrations of Au in island are tholeiites. Wide variations in the Au concentration are observed in rocks derived from primary magmas across a single volcanic area, and these can be positively correlated with the concentrations of incompatible elements such as Rb and Zr. These features are inherited from a S-depleted mantle source, since variable degrees of partial melting do not significantly affect the Au concentrations of the primary magmas. Copyright (C) 1997 Elsevier Science Ltd.