1. Slightly Weathered Boulder on Mars COSMOCHEMISTRY iLLUSTRATED Weathering Rinds on Mars “ Humphrey”, Gusev Crater, Mars ~30 cm NASA/JPL/Cornell

2. Weathering Rinds, Earth and Mars COSMOCHEMISTRY iLLUSTRATED Weathering Rinds on Mars Sak et al. (2004)McSween et al. (2004) Weathering rinds on a terrestrial boulder (Costa Rica) and on the Humphrey boulder on Mars. ~0.5 cm

3. Quantification of Rind Formation COSMOCHEMISTRY iLLUSTRATED Weathering Rinds on Mars Reaction transport models indicate minimum weathering times of at least 22 x 10 3 years for Humphrey. Hausrath et al. (2008)