Volume 1 of this treatise on feldspars provides a critical in-depth review of the vast primary literature on crystallography, physical properties, chemistry and microstructures of feldspars. It gives an integrated literature cover up to late summer 1986; an innovative feature is the citation of all literature published subsequently up to a few weeks before publication in a late reference list. The data were treated critically and, where possible, organized into tables. Most of the figures are new. In places new interpretations are presented. Important new aspects are treated extensively. These include the results of high-resolution TEM studies of modulated structures and microstructures, high-precision determination of trace elements in the ppm and ppb ranges, new dynamic experiments on diffusion in and on growth, dissolution and zoning of feldspars. Volume 1 is a completely rewritten condensation of volumes 1 and 2 of the first edition, but for convenience the same chapter headings were retained. It is important to note that Volume 2 (in preparation), which covers thermodynamics, phase relationships and parageneses, is completely new. It contains those chapters which were planned for the never printed Volume 3 of the first edition.