Phase transitions in minerals are of interest to a wide spectrum of scientists - geologists, mineralogists, solid state chemists, and physicists. We have now reached the point where mean field theory or Landau Theory of phase transitions as a function of temperature, pressure, or chemical composition can be usefully applied to natural materials, resulting in an improved understanding of the thermodynamics of significant constituents of the earth.

The fi eld trip described in this guide starts in the “Norwegian Alps,” the high mountain massif called Jotunheimen, and runs out along Sognefjorden, the world’s longest fjord, to the islands along the west coast of Norway. Geologically, the Sognefjord transect provides a complete cross section through the Caledonian orogenic belt, of Paleozoic age, which in Norway stretches along the west coast from Stavanger to North Cape, a distance of ~2000 km.

RESOURCES FOR THE FUTURE (RFF) is an independent nonprofit organization engaged in research and public education on natural resource and environmental issues. Its mission is to create and disseminate knowledge that helps people make better decisions about the conservation and use of their natural resources and the environment. RFF neither lobbies nor takes positions on current policy issues. Because the work of RFF focuses on how people make use of scarce resources, its primary research discipline is economics. However, its staff also includes social scientists from other fields, ecologists, environmental health scientists, meteorologists, and engineers. Staff members pursue a wide variety of interests, including forest economics, recycling, multiple use of public lands, the costs and benefits of pollution control, endangered species, energy and national security, hazardous waste policy, climate resources, and quantitative risk assessment. <...>

The solid part of the Earth is made up of rocks. Rocks are made up of minerals. A mineral is a naturally
occurring inorganic solid. It has a specific chemical composition and a characteristic crystal structure.
Quartz is a very common mineral. Most beach sand is composed of quartz. It has the composition SiO2
and forms elongate 6-sided crystals that terminate at a point <...>

Minerals are intrinsically resistant to the processes that homogenize silicate liquids—their compositions thus yield an archive of volcanic and magmatic processes that are invisible at the whole rock scale. Minerals and their inclusions record diverse magma compositions, the depths and temperatures of magma storage, the nature of open system processes, and the rates at which magmas ascend.

Melt inclusions (MI) are small droplets of melt now containing some combination of crystals, glass and vapor that are trapped in crystals formed in magmas. Over the past few decades, the study of MI has matured to become an accepted technique to investigate melt evolution in volcanic systems (Clocchiatti 1975, Roedder 1979, Lowenstern 1995, 2003, Sobolev 1996, Frezzotti 2001, Hauri et al. 2001, Anderson 2003, Schiano 2003). MI in volcanic rocks are commonly large (>50 µm), glassy and contained in fresh and transparent minerals, and are generally easy to identify. MI in volcanic rocks generally provide consistent and reasonable results concerning the chemistry of melts at depth and provide the best tool available for assessing the volatiles in magmas (Anderson 1973, 1974, Lowenstern 1994, 1995, 2003). The best MI are often found in the most rapidly cooled parts of pyroclastic deposits and glassy rinds of lavas, which are not so easy to find (A.T. Anderson, Jr., personal communication, 2006).

This book arose from a series of lectures given at the Universities of Cambridge and Oxford during the Spring of 1966. The lectures were based on material compiled by the author between 1961 and 1965 and submitted in a Ph.D. dissertation to the University of California at Berkeley. At the time crystal field theory had become well established in chemical literature as a successful model for interpreting certain aspects of transition metal chemistry.

We are facing a global mineral resource crisis. In fact, we have two of them. First, Earth has a finite supply of minerals for a population that is growing faster than at any time in history
(Figure 1.1). Second, mineral consumption is growing even faster than the population. Until recently, we were deeply concerned that most minerals were used in more developed countries (MDCs) with smaller consumption in less developed countries (LDCs) (Table 1.1).

The forms in which metals are found in the crust of the earth and as sea-bed deposits depend on their reactivity with their environment, particularly with oxygen, sulphur, and carbon dioxide. Gold and the platinum metals are found principally in the native or metallic form. Silver, copper, and mercury are found native, as well as in the form of sulphides, carbonates, and chlorides. The more reactive metals are always in compound form, such as the oxides and sulphides of iron and the oxides and silicates of aluminium and beryllium. The naturally occurring compounds are known as minerals, most of which have been given names according to their composition (e.g. galena—lead sulphide, PbS; sphalerite—zinc sulphide, ZnS; cassiterite—tin oxide, Sn02 ).

This book is designed to describe the basic principles used in the concentration of specific minerals from their ores. It further deals with the development of these principles in industry and the requirements for effective process control. The earlier editions were written in connexion with the teaching of mineral technology at the Royal School of Mines in London, and were designed to be used together with the laboratory study and plant experience essential for a sound grasp of this science and its applications. This correlation of principles and practice is continued here.