Siderite and ferric oxyhydroxides imply interlinked carbon, iron, and halogen cycles on Mars

Proceedings of the National Academy of Sciences, Volume 122, Issue 25, June 2025. <br/>SignificanceThe overall rarity of carbonate deposits on Mars have been interpreted to be the result of acid dissolution. We show that siderite is stable in Mars-relevant fluids from pH 7 to 2 and its alteration to ferric minerals—similar to those recently …