On Mars, phyllosilicate (clay) minerals are widespread in terrains that date back to the Noachian period, 4.1 to 3.7 billion years ago. Phyllosilicates are formed by the interaction of water with volcanic rock, leading many planetary researchers to conclude that there must have been sustained surface water, groundwater or active hydrothermal systems at some point in Martian history. But new research from Brown University suggests that the clays may...
