Summary of recommendations of nomenclature committees relevant to clay mineralogy: report of the Association Internationale Pour l'Etude des Argiles (aipea) nomenclature committee for 2006.

Brindley et al. (1951) reported the earliest efforts to obtain international collaboration on nomenclature and classification, initiated at the International Soil Congress in Amsterdam in 1950. Since then, national clay groups were formed, and they proposed various changes in nomenclature at group meetings of the International Clay Conferences. Most of the national clay groups have representation on the Nomenclature Committee of the Association Internationale Pour L\u2019Etude des Argiles (AIPEA, International Association for the Study of Clays) Nomenclature Committee, which was established in 1966, and no longer have ad hoc nomenclature committees. The precursor committee to the AIPEA Nomenclature Committee was the Nomenclature Subcommittee of the Comite Internationale Pour L\u2019Etude Des Argiles (CIPEA, International Committee for the Study of Clays). The AIPEA Nomenclature Committee has worked closely with other international groups, including the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), which is responsible for the formal recognition of new minerals and mineral names, and the International Union of Crystallography (I.U.Cr), which considered extensions to the nomenclature of disordered, modulated and polytype structures (Guinier et al., 1984) published earlier by a joint committee with the IMA (Bailey, 1977). In contrast to the other national clay groups, however, The Clay Minerals Society (CMS) Nomenclature Committee, which was established in 1963 at the same time as the CMS and predates the AIPEA Nomenclature Committee, remains in existence and occasionally produces recommendations. The precursor to this committee was the Nomenclature Sub-Committee, which was organized in 1961 by the (U.S.) National Research Council. The Chair of the AIPEA Nomenclature Committee is a standing member of the CMS Nomenclature Committee so that the committees are in close contact. The purpose of the AIPEA Nomenclature Committee has been to make general and specific recommendations concerning a) definitions of mineralogical and crystallographic clay-related terms, b) classification and terminology of clays, clay minerals and related terms, c) standardization of structural and descriptive terms, d) species, subgroup, and group names, e) the establishment of procedures/criteria for determining species, f) the emphasis (or re-emphasis) of the proper use of terms, and g) any additional aspects relating to nomenclature. Approximately twelve published reports have been presented since the 1950s. However, an additional twelve unpublished reports have been archived, and many committee papers have been written by guest members asked to join the committee to help resolve a specific issue or by committee members to help lead the discussion of a specific topic. Although the latter papers have not been published, many illuminate the rationale behind recommendations. In addition, they may also show insight in areas still in need of additional research. In general, the Committee is not expected to provide research to reach a recommendation. Instead, where sufficient data are unavailable, the Committee may (or may not) note the insufficiency and postpone any further comment. Thus, extensive committee papers may have been written, only to conclude that comment should be deferred