Hematite spherules at Meridiani: results from MI, Mini-TES, and Pancam - Calvin, W.; Shoffner, J.D.; Johnson, J.; Knoll, A.H.; Pocock, J.M.; Squyres, S.; Weitz, C.M.; Arvidson, R. E.; Bell III, J.F.; Christensen, P.; de Souza Jr., P.; Farrand, W.; et al. (Journal of Geophysical Research, 2008)