Long-range order in amphiboles

Comprehensive knowledge of the order-disorder relations in amphiboles is essential to (1) complete understanding of the crystal chemistry of these minerals, and to (2) the use of amphiboles in thermodynamic calculations (e.g., of temperature and pressure of equilibration) where accurate activity models are critical to the accuracy of such treatments. Moreover, such information is essential to our understanding of phase relations, optical and electrical properties and dehydrogenation mechanisms. As a result, more effort has been expended on characterizing site occupancies in amphiboles than in any other group of minerals. Hawthorne (1983a,b) reviewed in detail all work prior to 1983. Here, we will briefly summarize this work, and focus more on what has been learned since then.