Mystery solved: Why seashells’ mineral forms differently in seawater
For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth’s oceans: Why does calcium carbonate, the tough material of seashells and corals, sometimes take the form of calcite, and at other times form a chemically identical form of the mineral, called aragonite, that is more soluble — and therefore more vulnerable to ocean acidification? Researchers had previously identified variations in the concentration of magnesium in the water as a key factor in that process, but had never been able to explain why that produced such a dramatic effect. Now scientists at MIT and Lawrence Berkeley National Laboratory (LBNL) have carried out a detailed, atomic-level analysis of the process. The new explanation, they say, could be a step toward enabling the directed synthesis of new materials on demand in the lab. The findings are published this week in the Proceedings of the...