- © The Mineralogical Society Of America
The time is ripe for a fresh inventory of occurrences of amphibole-group minerals in igneous rocks. Here, I build on the available resources, for example on the review of Wones and Gilbert (1982) in volume 9B of the RiMG series. They entitled their chapter “Amphiboles in the Igneous Environment.” I adopt the same title, but intend to make the scope of my review somewhat broader by including non-igneous rocks formed in the igneous environments. Much has been written about occurrences of amphibole-group minerals over the last quarter of a century, much of it ably summarized by Deer et al. (1997), and it is quite impossible to do more here than to summarize representative findings concerning the textural development and broad compositional features of minerals of the amphibole group that are important in igneous contexts. Amphibole-group minerals are widespread in igneous rocks produced in zones undergoing extension, as well as in rocks associated with subduction systems. Each setting may be associated with specific late-stage metasomatic phenomena in which amphibole-group minerals play a key role. Metasomatic overprints involving an amphibole also are widespread in the mantle, and act as an essential step in the fertilization of sterile mantle if it is to produce alkali basaltic magmas by partial melting. Finally, selected findings are summarized here on amphibole-group minerals in igneous environments in other parts of the solar system.
Amphibole-group minerals have generally been underutilized in petrological studies. Reasons are not hard to find. The full characterization of an amphibole presents serious challenges, so much so that most investigators have been constrained to examine only those major elements that can be assessed in routine electron-microprobe analyses. As Hawthorne and Oberti (2006) pointed out in their essay on the future of schemes of classification, it has become abundantly clear that progress is within …