The Clay Minerals Society

Glossary for Clay Science Project

The Clay Minerals Society (CMS) Nomenclature Committee was asked by CMS Council to produce a glossary of clay science in 2003.

Constraints and goals of the Glossary. The Committee developed several constraints on the development of the glossary:

(1) it was decided to produce a glossary of clay terms, based on clay science. Terms may have other meanings in other disciplines, but the Committee did not want to include how other disciplines may use the terms (unless it is integral to the definition, e.g., as was the case of “particle size” for “clay”). The definitions provided below are terms as used in clay science and thus, this glossary is not a compendium, as is the case for the AGI Glossary. However, the definitions do not and should not stray from the basic science definitions as one would have in chemistry and physics. The point here was to include examples and perhaps direct the discussion toward clay science; the definition itself would conform to definitions in the other sciences. Unlike the AGI Glossary, where current usage is given even if that usage deviates from the original definition, the CMS Glossary provides the original definition and explains how the word may be currently and, perhaps incorrectly, used.

(2) Provisional or tentative definitions were avoided. The glossary may be used in ways that we may be unaware, such as by the legal profession, and the Committee only listed terms that are well defined. Definitions in contention that could not be reconciled in committee were not included. Multiple definitions are provided, if warranted, and discussion is provided on how the terms may have changed in meaning over (recent) time.

(3) Established definitions by the International Mineralogical Association (IMA), CMS, and Association Internationale pour l’Etude des Argiles (AIPEA) Nomenclature Committees, or any other international body were not open for discussion. The Committee decided that further explanation may be warranted to show the utility of a term in clay science, but the definition is given unchanged from that provided by the international body.

(4) In general, computer-program names and similar names are not part of the Glossary, both because such names tend to be ephemeral and because the Society does not advocate the use of a specific program.

The initial effort was not to include mineral and related (i.e., discredited, synonyms, etc.) names, although group names were included in what is now considered Part 1. There are other web sites that have compiled mineral name lists, although descriptions on other websites tend not to be oriented toward clays. The 2018 edition of the Glossary included a first draft of “Part 2. Clay-related materials (excluding exchanged phases)” that covers clay-related minerals, discredited names, and synonyms, with approximately 650 terms. Any natural material that would be commonly found in a clay-related publication are considered in Part 2.

Glossary