COMMENT ON THE RATE OF PYRITE DECOMPOSITION ON THE SURFACE OF VENUS

Fegley et al. (1995, B. Fegley Jr., K. Lodders, A. H. Treiman, and G. Klingelhoffer. Icarus 115, 159-180,) describe a series of furnace expe riments in which the mineral pyrite was decomposed in various gas envi ronments, They use these data to estimate the rate of pyrite decomposi tion on the surface of Venus, The issue of the presence or absence of pyrite on the Venus surface is of significance because pyrite has an i mportant potential effect on the electromagnetic properties of planeta ry surface materials sensed by radar (1997, J. A. Wood. In Venus II (S . Bougher, D. M. Hunten, and R. Phillips, Eds.). Univ. of Arizona Pres s, Tucson, AZ, in press). We argue that the decomposition rates found by Fegley et al. are not applicable to the surface of Venus, because n one of the gas environments used by those authors accurately reproduce d the atmospheric composition at the Venus surface. (C) Academic Press .