Organic molecules often come in two mirror-image forms, often referred to as "right-handed" and "left-handed". This handedness is called chirality. For example, the amino acid alanine comes in a right-handed (D-alanine) and a left-handed (L-alanine) form. Living cells are very selective, choosing amino acids only in the left-handed form and sugars in the right-handed form. However, most abiotic processes produce an equal amount of each. Somehow life must have developed this preference (homochirality); but while scientists have proposed several theories, they have no consensus on the mechanism.
Hazen investigated the possibility that organic molecules might acquire a chiral asymmetry when grown on the faces of mineral crystals. Some, like quartz, come in mirror-image forms; others, like calcite, are symmetric about their centers but their faces come in pairs with opposite chirality. With Tim Filley, an expert at organic chemical analysis, and Glenn Goodfriend, a geochemist, Hazen cleaned large calcite crystals and dipped them into aspartic acid. They found that each face of the crystal had a small preference for either left- or right-handed forms of aspartate. They proposed that a similar mechanism might work on other amino acids and sugars. This work attracted a lot of interest from the pharmaceutical industry, which needs to produce some of their drugs with a pure chirality.