Formation of iron-rimmed sandstone nodules on earth; terrestrial analogue for the formation of Martian blueberries?

NASA\u27s twin Mars Exploration Rovers, MER, Spirit and Opportunity, have identified numerous geologic features that hint at a watery past on Mars noted in Malik, 2004. Prominent among these features are the Martian Blueberries that occur as spherical hematite (Fe₂O₃) nodules. Hematite formation is facilitated by the presence of water, although there are presently no known sources of free liquid water on Mars. Chan et al., 2004 states that these blueberries are also similar to nodules found in the Jurassic aged Navajo Sandstone in Utah. An understanding of the processes controlling the formation of the Utah nodules may thus be key in determining the processes of nodule formation on Mars --page iii