The name bentonite always arouses the curiosity of people hearing it for the first time. It was initially suggested at the end of the 19th century by W.C. Knight, an American geologist, after a rocky formation near Fort Benton, where a deposit was found of a particular type of water swelling clay, called “mineral soap”. A few years earlier, around mid 19th century, a plastic clay mineral had been identified and studied in Montmorillon, France, and later called montmorillonite. It should be pointed out, however, that swelling clays have always been used by man, and there is a lot of evidence testifying to their use since very ancient times. Even in Fort Benton, bentonite had been known for quite a long time: as a matter of fact, pioneers had reported that a special clay that would swell in water was used by the natives to wash their clothes. For almost 30 years since the discovery of this deposit, both production and use of bentonite had remained insignificant. A wider interest in bentonite began only around the ’20s of the last century. Actually, the current use of the name bentonite goes back to those years when two researchers, Ross and Shannon, suggested to call bentonite a whole range of clays, that had formed through volcanic ash decomposition and mostly consisting of the clay mineral montmorillonite and of lesser amounts of other minerals, like quartz, feldspar, pyrite, and calcite.