ROCKS AND MINERALS OF THE WORLD: Collins Discovery Guides

220 of the commoner rocks and minerals of Europe are listed in this pocket guide, with each example being photographed in colour in its ideal form, often from a specimen in a museum. Additional aids to identification, key features and distribution are included. The rocks are divided into 15 categories, for instance carbonates or sedimentary, and within those categories the entries are alphabetically listed and they also appear in the index. A general introduction to different kinds of rock covers background information such as their formation, mineral content and textural features. The seven different mineral crystal structures are colour-coded, and there are scales to indicate hardness and specific gravity. The book begins with the family of elements, including Copper which is found in igneous and volcanic rocks, Diamond which occurs at high pressure in the earth's mantle and Gold, associated with hydrothermal veins related to quartz. The Quartz family itself has some spectacular crystals, including the mineralised vein systems of Chalcedony, raw Amethyst or a cut gem of Citrine. Opal in this family has almost no crystalline structure but boasts a distinctive play of opalescent colour. The rock section includes everyday slate, clay and coal, and the book concludes with meteorites and impactites. 243pp, softback, colour photos on each double spread.