The use of a polarizing microscope is still an essential tool for every earth scientist who does petrographic work. No student in mineralogy, petrography and petrology, geology and mining geology should leave university without knowledge of this fundamental method for determining minerals and rocks, which in 1850 revolutionized our science and placed it on firm foundations.

In German geological literature, this is the first short comprehensive teaching book about using a microscope in the identification of minerals for at least fifty years. The classic German works of this kind, such as those by Weinschenk (1915) and Chudoba (1932), opened up polarizing microscopy to earlier generations, including one of the authors (H.P.) These have long been out of print and outdated. Therefore, in order to close this gap and to provide future earth scientists with guidelines in practical microscopy, we have compiled these notes, which have been used and developed over many years at the Mineralogical Institute in Tubingen. In writing this book the following guidelines were used:

Tt is 50 years since the publication of the first edition of this volume of Rock-forming Minerals. The intervening years have seen a vast growth in the range and quantity of published work on 'non-silicate" rock-forming minerals, a growth that has justified dividing the topics of the first edition into two volumes (sulphates, carbonates, phosphates and halides have already been covered; see Chang, Howie and Zussman, Rock-forming Minerals, Vol. 5B, 2nd edn. The Geological Society, 1996). Here, we discuss the oxides, hydroxides and sulphides. This growth in published information on oxide, hydroxide and sulphide minerals has resulted partly from the availability of new techniques for the chemical and structural analysis of these materials and the characterization of their physical and chemical properties. It has also been the result of the opening-up of entirely new fields of investigation where these minerals play a key role. The list of minerals discussed in this new edition has expanded somewhat compared with the first edition; although the same five sulphide minerals are considered "rock-forming', the hydroxides have gained several new iron hydroxide phases (akaga-neitc. ferrihydrite and feroxyhyte), while losing limonite. These developmenb are largely due to better characterization of poorly crystalline ultrafine particle phases using new techniques. The list of oxides has also expanded with additions including quandilite. pseudonitile and armalcolite, the last a lunar mineral and a legacy of the Apollo missions which occurred seven years after publication of the first edition.

For this completely new edition of Rock-Forming Minerals we have maintained the general principles and organization adopted for the first edition. The past twenty years, however, have seen an enormous expansion in activity in the Earth Sciences as a whole, and the subjects of Mineralogy and Petrology have certainly not been exceptions. The terms 'literature explosion* and 'exponential growth', although almost cliches, nevertheless are very apt in the present context. Not only have the numbers of researchers and their outputs increased, but exceptional growth has occurred in three particular fields: electron microprobe analysis, experimental petrology, and the determination of crystal structures.

The facility of rapid and accurate electron probe analysis has replaced to a great extent the more laborious chemical and optical analytical methods, giving many more reliable analyses for each mineral and enabling researchers to examine more specimens and to complete a wider range of studies in a shorter time. The availability of more well-analysed material has also led to much more significant discussion of chemical variations and their relationships with crystal structure, physical properties and, most of all, parageneses. The important phenomena of fine-scale intergrowths (exsolution, etc.) and of chemical zoning have also been much more readily investigated using electron probe and other electron-optical methods.

The study of phase equilibria at elevated pressures and temperatures has continued apace, so that the cumulative number of systems which need to be described has grown. In addition, much wider ranges of pressure and temperature have become accessible with improved techniques. At the same time, there has been a growth in the determination of thermodynamic properties of minerals, and in the experimental and theoretical approaches to element distribution within and between minerals.

The advent and growing use of automatic single-crystal diffractometers has made it possible to determine crystal structures much more quickly, so that whereas there was hitherto perhaps one published structure for a mineral or even for a mineral group, now there can be structure determinations for a mineral at each of several chemical compositions, and at a number of different temperatures.

The above, and other growth areas in mineralogy, have led to the fact that in this new edition the average number of pages devoted to each mineral is about three times that for the first edition. The extent of growth is indicated also by the list of references for each mineral which for this volume we have attempted to bring up to date to 1979, and the early months of 1981.

Rockbursts are a dynamic hazard induced by tunneling (Fig. 1.1.1). Many rockbursts have occurred in highway tunnels: in Norway (Myrvang & Grimstad, 1983); the Kanetsu tunnel in Japan (Saito, Tsukada, Inami, Inoma, & Ito, 1983); the Karisaki tunnel in Japan (Katusyama, 1994); tunnels in China (Tjong Kie, 1988); a waterway tunnel in Korea (Lee, Park, & Lee, 2004); the Gotthard Base Tunnel in Switzerland, where the deepest point has a rock layer of 2450 m (Hagedorn & Stadelmann, 2008); tunnels at Tianshengqiao II Hydropower Station in China (Zebin, 1994); headrace tunnels at Taipinyi Hydropower Station in China (Wang & Hong, 1995);