Isothermal compressions of molten Fe2SiO4 have been measured between 1.0 and 5.5 GPa in a piston-cylinder apparatus by observing sinking and floating of ruby and garnet buoyancy markers of known composition and density. For liquid Fe2SiO4, (d&rgr;/dP)1773 K is 0.080 g cm-3 GPa-1 in the pressure range investigated. The static compression sink/float density measurements, when combined with the 105 Pa reference density from Shiraishi et al. [1978>, yield a third order Birch-Murnaghan bulk modulus for molten Fe2SiO4 of K1773 K=24.4 GPa with a pressure derivative dK/dP=10.1. ¿ American Geophysical Union 1992