Froth flotation is an outstanding example of applied interfacial and colloidal science. It has roots in the nineteenth century discoveries concerning the separation and concentration of valuable minerals from ores, and is considered as one of the most important achievements of the twentieth century, which has significantly contributed to the vast expansion of the raw material industry. Efforts to understand the mechanisms governing flotation led to the research into the wetting and dewetting statics and dynamics, and the intervening free and wetting liquid films as early as the 1930s. Surface forces operating across the films were also appreciated at that time. These efforts have provided stimuli for advances in the theory of interparticle forces with the development of several sophisticated experimental techniques <...>

A requirement for geostatistical prediction is estimation of the variogram from the data. Often low sample size is a major impediment to elucidating a variogram even for a highly autocorrelated spatial process. This paper presents a methodology for improving variogram estimation when samples exist from multiple years or regions sharing a similar process for generating spatial autocorrelation.

This collection of papers is aimed primarily at the environmental geoscientist faced with the challenges of communicating important scientific results to those who might benefit from them, whether they are politicians, policy-makers, potential victims of geological disasters, fellow scientists or other members of the public. Environmental geoscience has grown to become one of the most important disciplines of geoscience as a whole, and scientific methods of investigation have become sophisticated and effective at addressing numerous problems that directly affect health and safety. The audience for such research thus is wide, and for such research to be used in the most effective manner requires well-developed communication skills to reach an audience that varies greatly in education and ability to comprehend scientific concepts. The implications of failing to communicate effectively may be severe: geological disasters have had a massive economic and social impact, with major loss of life.

This comparative geochemical study of jasperoid in the northern Great Basin is based on 65 samples from 10 Carlin-type gold deposits and 22 similar but apparently barren hydro-thermal systems. Multielement geochemistry coupled with oxygen isotope data indicate that hydrothermal fluids in barren and mineralized systems evolved in different ways, and that there are fundamental geochemical differences among the various gold-producing deposits of the area.

Much of the variation in the jasperoid geochemical data can be explained in terms of seven abstract end-member components obtained through factor analysis. Three of these components (factors) dominate the results and are related to common products of alteration and mineralization in epithermal systems of the northern Great Basin. Element associations for these factors are: factor 1: Ti02, Al203, La, K20, Sr, Fe203, Th; factor 2: Au, Ag, Sb, Si02> As, Pb; and factor 3: W, B, V, Zn, Co, Au, CaO, Ni, Mn, Cu.