This 2nd edition contains the same essentials of the QAPF and TAS classification systems as the 1st edition, but with a few corrections and updates. Bigger changes have been made in the area of the alkaline and related rocks. In the ten years between the 1st and 2nd editions, several Working Groups have been working hard on the kimberlitic, lamproitic, leucitic, melilitic, kalsilitic, lamprophyric and picritic rocks with varied success. The Subcommission thanks each member of the Working Groups for their assiduous and constructive contributions to the revised classifications. Being too numerous to identify individually here, they are named in Appendix A.

The lamproites and kimberlites continue to defy precise classification, but we do now have improved characterizations rather than the definitions normally required to give limits between one rock type and the next. The work of the Subcommission continues, not only to resolve these problematic areas but also to tackle new issues as they arise. With the publication of the 2nd edition, I shall retire from the chair and am pleased to pass the reins over to the capable hands of Prof. Bernard Bonin of Université Paris-Sud.

Particular tribute is due to the late Albert Streckeisen who died during the early stages of preparation of this 2nd edition. His long association with igneous rock nomenclature began in earnest in 1964 when he published a review article in which he evaluated the dozen igneous rock classifications current at that time.