Published online by Cambridge University Press: 14 March 2018
Samples of the argille scagliose from various localities in the Modenese Apennines have been studied by optical, X-ray and d.t.a, methods as part of an investigation into the composition and origin of this remarkable allochthonous formation. Illite, chlorite and a kaolinitic mineral of “fireclay” type are widespread. Samples from one locality contain also a conspicuous 22–28 Å swelling chlorite, the origin of which is discussed. It is as yet uncertain whether this mineral is confined to clays containing exotic blocks of ophiolite (greenstone) or whether it is more widely distributed.