Non-biological processes do not generally distinguish between L and D variants. This step, known as chiral selection, is crucial to forming chainlike molecules of pure L amino acids. Hazen and his research team did a simple experiment, where they immersed a fist-sized crystal of the common mineral calcite, which forms limestone and the hard parts of many sea animals, in a dilute solution of the amino acid aspartic acid. Most minerals are centric, meaning that their structures are not handed. However, some minerals display pairs of crystal surfaces that have a mirror relationship to each other.
Calcite is one such mineral.
Calcite is common today, and was prevalent during the Archaean Era some 4 billion years ago when life first emerged. Since the pioneering work of Stanley Miller in the 1950s, prebiotic synthesis of amino acids has been shown to be relatively easy. Our experiments demonstrate that crystal faces of calcite easily select and concentrate the amino acids. Experiments now underway will see if the calcite also promotes the formation of amino acid chains. The Carnegie Institution of Washington has been a founder of basic scientific research since 1902.