What makes one clay kill bacteria, and the other promote growth? And why do most clays tested have no effect? Research like that being done by Williams and Haydel can answer such questions. "Clay can be as variable as the bacteria we are studying. There is a lot to be learned yet," Williams notes.
Clay's properties fuel interest
Williams' career fascination with clay started when she was a mineral exploration geologist looking for ore deposits. She worked with 'the father of clay mineralogy,' Bob Reynolds, at Dartmouth College. Later, as a research associate at Louisiana State University, a colleague was studying geophasia ?eating clay, a behavior seen in animals and people, since the time of the aborigines.
"In the South Appalachian Mountains, poor women would eat the local clay to help soothe nausea and stomach ailments, particularly during pregnancy. The clay was rich in kaolinite. (Kaolinite is the major ingredient in the over the counter remedy Kaopectate). But one day, they ran out of clay and moved over to another mountain and people began dying. We wanted to know why."
The key to clay's variable nature seems to be its structure. "Clay is a mineral; it has a crystalline structure that is both flexible and fluid," Williams says. She likens them to very thin, two-nanometer-thick slices of bread in a "peanut butter and jelly sandwich." The "bread" is composed of three regions, two silicate layers with tetrahedral rings bo
Source:Arizona State University