Structural studies of OH in nominally anhydrous minerals (NAMs) using NMR

Nuclear magnetic resonance (NMR) is a technique that is used very widely throughout science and medicine. There are approaching 20 journals devoted exclusively to NMR and magnetic resonance imaging, and well in excess of 10,000 papers published annually which involve this family of techniques. It has found extraordinarily diverse applications, and its applications to inorganic solids such as minerals represent a very small part of NMR as a whole. There had been occasional NMR studies of minerals since the discovery of the NMR effect in 1946, but until the early 1980s, the large width of NMR resonances in the solid state precluded widespread application of the technique. The most important factor in the application of NMR to minerals was the development of magic angle spinning (MAS), a technique for narrowing lines in solid state NMR. More recently the development of more complex sample spinning arrangements and multiple pulse methods together with the availability of ever higher magnetic fields opens up more and more possibilities for NMR in mineralogy and geochemistry. NMR is far too diverse and complex for the whole subject to be covered here, so this review will be tightly focused on aspects which relate to understanding the structural role of water in nominally anhydrous minerals. Two review papers (Kirkpatrick 1988; Stebbins 1988) in the "Reviews in Mineralogy" volume on Spectroscopic Methods in Mineralogy and Geology provide an excellent starting point for Earth scientists wishing to learn more about NMR in general. More recent reviews aimed at Earth scientists include those by Fechtelkord (2004) and Kohn (2004), more general reviews of NMR of inorganic solids include Engelhardt and Michel (1987) and MacKenzie and Smith (2002). The web page maintained by J.P. Hornak (http://www.cis.rit.edu/htbooks/nmr/) is also an extremely good resource.