An Introduction to the Rock-Forming Minerals

In this edition of Introduction to the Rock-Forming Minerals, most of the commonly occurring minerals of igneous, metamorphic and sedimentary rocks are discussed in terms of structure, chemistry, optical and other physical properties, distinguishing features and paragenesis. Important correlations between these aspects of mineralogy are emphasized wherever possible. The content of each section has been updated where needed in the light of published research over the 21 years between editions. Tables of over 200 chemical analyses and formulae are included and a number of older entries have been replaced by more recent examples. Major new features include: Entirely new views of crystal structures in perspective using CrystalMaker colour images; CrystalViewer interactive CD with >100 mineral structures included; Over 60 colour photographs of minerals in thin sections of rocks under the petrological microscope; Considerably expanded treatment of feldspar and zeolite minerals; Mineral identification table based on birefringence and listing other properties; and Colour strip with appropriate interference colours and birefringences for the main rock-forming minerals. This book will be useful to undergraduate students of mineralogy, petrology and geochemistry, especially those at third or fourth year, engaged in more advanced courses or specialized projects, and also as a reference work for students for ‘Masters’ degrees by taught courses or research. For doctorate students, and research workers in the Earth Sciences as well as those in Materials Science and other related disciplines, this work can be useful as a condensed version of the very extensive treatment presented in the volumes of the DHZ Series ‘Rock-Forming Minerals’, second edition.
Staurolite (Fe2+,Mg,Zn)3-4(Al,Fe3+,Ti)17-18O16[(Si,Al)O4]8H3-4
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Published:January 01, 2013
Abstract
The staurolite structure is based upon an approximately cubic close packed array of oxygens with mainly (Al,Fe,Mg) in its octahedral and (Si,Al,Fe) in its tetrahedral interstices. It can be described also in terms of (010) slabs of the kyanite (Al2SiO5) structure alternating with layers of cations in octahedral and tetrahedral coordination with basic composition AlFe2O3(OH), but capable of exhibiting a wide range of cation substitutions (see below). The two components are labelled K and S, respectively, in Fig. 31. In the S layer the Al octahedra share edges forming chains parallel to the z axis. The ideal overall formula for staurolite is H2Fe2+4Al18Si8O48 but analysed staurolites contain between 2 and 4 hydrogens per formula unit. This would result in a net positive charge, but it is balanced by substitutions such as Al for Si, or Mg,Fe2+ for Al and also by only partial occupation of some cation sites. A different view of the staurolite structure is that given by the polyhedral model shown in perspective in Fig 32.