The ever increasing number of publications about minerals reflects a growing interest in nature. Most of those publications though only deal with a few dozen of the most common minerals or gemstones. This book fills the gap by also featuring less common and rare minerals. The authors describe over 600 mineral species and varieties, illustrated with about 750 color photographs. In choosing illustrations of particular minerals, aesthetic criteria such as size of crystal and color played a role in addition to their importance and distribution in nature. This book includes some rare minerals, known only from one locality, because they form very attractive crystals or aggregates. There are minerals known to humankind since prehistoric times such as quartz and gold, but also minerals first described quite recently like rossmanite. The photographs show well-formed and colorful crystals but many-aggregates, which are more common in nature, are also included. The minerals in the book are listed according to the mincralogical system of Hugo Strunz, in his book Mineralogische Tabellen in 1978. The chemical formulae of individual minerals follow the form of Glossary of Mineral Species 1995 by M. Fleischer and J.A. Mandarine The information is complemented in both cases with the latest knowledge from scientific literature, such as new nomenclature of amphiboles, micas and zeolites. The mineral descriptions cover the basic physical and chemical data, including chemical formula and crystal system. The data provided correspond mainly to the end-members. The less common valence of the chemical elements is marked in the chemical formula (FeJ, Mn", As", Mn4", Pb'). Where an element features in both valences in the mineral, they are both marked (e.g. ilvaite, braunite).

Grey and white carbonate mylonites were collected along thrust planes of the Helvetic Alps. They are characterised by very small grain sizes and non-random grain shape (SPO) and crystallographic preferred orientation (CPO). Presumably they deformed in the field of grain size sensitive flow by recrystallisation accommodated intracrystalline deformation in combination with granular flow. Both mylonites show a similar mean grain size, but in the grey mylonites the grain size range is larger, the grain shapes are more elongate and the dynamically recrystallised calcite grains are more often twinned. Grey mylonites have an oblique CPO, while the CPO in white mylonites is symmetric with respect to the shear plane. Combustion analysis and ТЕМ investigations revealed that grey mylonites contain a higher amount of highly structured kerogens with particle sizes of a few tens of nanometers, which are finely dispersed at the grain boundaries.

During deformation of the rock, nano-scale particles reduced the migration velocity of grain boundaries by Zener drag resulting in slower recrystallisation rates of the calcite aggregate. In the grey mylonites, more strain increments were accommodated by individual grains before they became refreshed by dynamic recrystallisation than in white mylonites, where grain boundary migration was less hindered and recrystallisation cycles were faster. Consequently, grey mylonites represent 'deformation' microfabrics while white mylonites are characterised by 'recrystallisation' microfabrics. Field geologists must utilise this different deformation behavior when applying the obliquity in CPO and SPO of the respective mylonites as reliable shear sense indicators

The study of rocks and other mineral associations, especially of ore deposits, starts out from the purely descriptive. The composition of these materials, their geologic position in the most comprehensive sense, and their gross and fine structures and textures, etc., must be established. Further research must explain, first the "How"', then the "Why". The latter must comprise the interpretation of the association of materials and geologic position as well as each detail of texture and structure, even the smallest. On the knowledge obtained, one must build further and must generalize. Things of which the "Why" can be explained directly will serve in the explanation of others. In doing this the danger of circular reasoning will exist ; criticism is therefore invariably necessary, self-criticism most of all. The interpretations must, if possible, be reached along several paths, and the validity of the various paths must be carefully considered. <...>

Many scientists traditionally believe that the ore (and not only ore) matter of most endogenous economic minerals comes directly from the mantle or through the mantle matter differentiation and invasion of differentiated magmas in the crust together with water fluids rising from Earth’s depth. However, this assumption is right only in part as the entire matter of the continental crust, including ore elements, had been indeed released in the past from the mantle along with the other rock-forming oxides. In substance, however, this assumption is the “path of least resistance” as it allows us to hide our lack of knowledge of the real mechanisms of local crust enrichment with trace elements in a “black box” of the mantle and to substitute one complex problem with another one, no less complex. Indeed, the entire complexity of the classical approach to explaining the formation causes of local ore and other trace element accumulations in Earth’s crust is in that the concentration of most of them in the mantle is disappearingly low, whereas in commercial deposits it is relatively high and reaches sometimes top-cut grade value. For instance, gold and uranium concentration in the present-day mantle is on the order of 10-9; mercury and thorium 10-8; silver, tantalum, tungsten, platinum and lead 10-7; lithium, niobium, molybdenum and tin 10-6, etc., whereas in commercial deposits the concentration of these rare elements may rise to fractions and even whole percentages. <...>