The non-clay and clay mineralogy of the British argillaceous sedimentary rocks are discussed. The non-clay mineralogy is only considered in general terms due to the lack of detailed information. The general nature of the clay minerals, their genesis and the effects of burial diagenesis on clay minerals are reviewed. This is followed by a more detailed examination of the clay mineralogy of the Palaeozoic, Mesozoic and Tertiary argillaceous rocks. Consideration is given to the relative importance of the depositional environment and burial diagenesis in forming the clay assemblages now found in British mudrocks.
The petrology of the argillaceous sedimentary rocks is discussed in general terms. The use of electron microscopy in the examination of mudrocks generally and some British examples in particular is reviewed, including a discussion of the nature and origin of fissility. The possibility of using high voltage electron microscopy in future studies of argillaceous sediments is proposed based on its successful use in examining the microstructures and mineralogy of slates.