Abstract
It is now generally accepted that species names can be given to regularly interstratified clay minerals, in accordance with the recommendation of the AIPEA Nomenclature Committee (Brindley & Pedro, 1970). In Part A of this report we suggest (i) criteria for defining the degree of regularity of alternation of different layer types that should merit a name, (ii) data that should be provided for documentation of a regular interstratification, and (iii) some examples of interstratifications that do not merit names. In Part B of the report we apply the suggested criteria to the analysis of regular interstratifications previously reported in the literature, and make recommendation regarding the usage of existing names.