A preliminary investigation has been made of the bentonite beds in Billingen, Vestergötland, Sweden. The clay consists of a complex mixed layer mineral; the layers are mostly illitic and are mixed with probably chloritic and partly dehydrated montmorillonite layers. This clay mineral differs from the types found in the corresponding beds at Kinnekulle, 30 km, NW of Billingen, but is similar to the clay mineral found in the K-bentonites of Pennsylvania. Chlorite is present in varying amounts.