A REPORT ON THE DERIVATION AND PROPER USE OF THE TERM ANORTHOSITE*

TOMAS FEININGER
Centre géoscientifique de Québec, Case Postale 7500, Sainte-Foy, Québec G1V 4C7

* Geological Survey of Canada contribution number 42992.

Abstract

The term anorthosite, coined by T. Sterry Hunt in 1862, applies only to a specific rock type. The origin of the term and a review of the definition of anorthosite are given, as well as six recommendations on relevant petrographic nomenclature. The recommendations call for adherence to the IUGS definition of anorthosite, use of modifiers where appropriate (andesine anorthosite, augite anorthosite, and so on), abandonment of such meaningless expressions as anorthositic gabbro and gabbroic anorthosite, and use of the term meta-anorthosite where evidence of igneous parentage has been erased by deformation and metamorphism.

Keywords: anorthosite, petrography, terminology.