'Every person on earth uses, either directly or indirectly, ten metric tons of minerals each year.' So write Dr R. V. Dietrich and Dr Brian J. Skinner in their new book Gems, Granites, and Gravels. Minerals and mineral products are involved in all aspects of our lives; we depend on them to keep us alive and ensure the continuity of our society. As a consequence, they have been a source of fascination and study throughout human history. In this book, Drs Dietrich and Skinner consider not only the beauty of minerals and rocks, but also their utility and their roles in our everyday well-being. Gems, Granites and Gravels is a valuable introduction to mineralogy and to related specialities such as petrology (the study of rocks), crystallography (the study of crystals), and soil science. Discoveries in these fields are described in a historical context, while the authors explain what minerals and rocks are, how they are distributed around the world, how we depend on them, and where to see the most beautiful specimens of both minerals and rocks. This book will appeal to anyone interested in natural history and curious about rocks and minerals, including rock and mineral collectors, students of geology, and professional geologists.

Experts agree that the earth will eventually run out of certain low-cost, nonrenewable resources, possibly as early as a century from now. Will the transition to reliance on other, more abundant resources be smooth or discontinuous? Might industrial societies experience a marked decline in living standards-a radically different kind of society from the one we now know? Geologists maintain that once inexpensive high-grade resources are exhausted, economic growth will slow. Economists are more optimistic: they believe that new technologies and materials will be substituted rapidly enough to prevent minor economic dislocations. Toward a New Iron Age? takes an important step toward reconciling these divergent views. It is the most comprehensive study of the economic consequences of resource depletion-in particular, it is a thorough exploration of the prospects for one key metal, copper. The authors draw on geological and engineering data to calculate the resources now available and to assess the feasibility of substituting alternatives. Using linear programming and a range of hypothetical base conditions, they are able to estimate the course, through the next century and beyond, of several crucial factors: the rate at which copper resources will be used and when they will be depleted; how the price of the metal will fluctuate; when alternative materials will be substituted, in what patterns, and at what costs. By the late twenty-first century, the authors believe, low-cost copper will no longer be available. Industrial societies will have to operate on more abundant resources such as iron, silica, and aluminum. They will enter, in short, a New Iron Age.