Mining and metals continue to be among the best performing global equity sectors, but conflicting issues – from “pricing bubbles”, “imminent recessions”, “demand destruction” to “resource scarcity”- are confusing investors. Nevertheless, the importance of mining to the world has become very apparent in recent years, as commodity and equity prices have exceeded most expectations.
Therefore, investments in commodities become more attractive as a long-term investment as they are a safe haven in times of  economic crisis and provide a protection against currency devaluation. Thus, it is useful to know how to value metals and mining companies <...>

On the basis of textural features and spatial distributions, both supergene and hypogene origins have been proposed for alunite in sediment-hosted micron gold deposits. If alunite is indeed primary, its presence provides important constraints on the chemistry of the ore fluid. Thus, determination of the genesis of alunite is critical to the understanding of the geologic history of these ore deposits.

At the Post deposit in Nevada K/Ar ages of alunite are much younger than the age of mineralization. Sulfur isotope compositions of alunite from several sediment-hosted micron gold deposits are virtually identical to those of sulfides, suggesting that alunite sulfur came from quantitative (closed-system) oxidation of primary sulfide minerals during weathering. Sulfur and oxygen isotope compositions of barite are markedly different from those of alunite. The oxygen and hydrogen isotope compositions of alunite fall in the supergene alunite fields; data for cogenetic kaolinite fall on the kaolinite line, whereas those for hypogene kaolinite do not. From all available petrographic and geochemical data, it would appear that alunite in the micron gold deposits of Nevada is entirely of secondary supergene origin.

Africa holds extraordinary prospects for the paleontological investigation of mammalian evolution. Largely still inhabited by relic Plio-Pleistocene mammalian faunas, it is populated by animals such as giraffes, rhinos, lions, gazelles, zebras, okapis, and giant forest hogs, as well as descendants of endemics of longer residence such as hyraxes and catarrhine primates, beneficiaries of having been sheltered from the most extreme effects of climate and ecological change due to the position of the landmass astride the equator, the only continent to span both northern and southern temperate zones (Sanders and Werdelin, 2010). Occupying 20% of the world’s landmass, Africa is home to approximately a quarter of all living mammals (Kingdon, 1997; Medellín and Soberón, 1999), encompassing a tremendous range of species and adaptations, fostered by the size and physical and ecological heterogeneity of the continent (Kingdon, 1989; O’Brien and Peters, 1999). <...>

2-D and 3-D physical modelling of lithospheric convergence in the Luzon-Taiwan-Ryukyu region is performed with properly scaled laboratory models. The lithospheric model consists of two pails, continental (the Asian Plate, AP) and oceanic (the Philippine Sea Plate, PSP). The oceanic lithosphere has one layer, while the continental lithosphere includes both mantle and crustal layers. The continental margin is covered by sediments. A low-viscosity asthenosphere underlies the lithosphere. The opposing Luzon and Ryukyu subduction zones are initiated by inclined cuts made within the PSP. The subduction/collision is driven by a piston. Pre-collisional intraoceanic subduction along the Luzon and Ryukyu boundaries results in the formation of a transform zone between them, with two tear faults at the ends. The PSP undergoes strong compression along this zone. Subduction of the Chinese margin under the Luzon boundary further increases the compression. Compressive stresses reach the yield limit of the PSP in the arc area, which is a weak zone in the experiments. The plate fails at the western side of the arc along an eastward dipping fault, the Longitudinal Valley Fault. Underthrusting of the frontal wedge of the PSP along this fault results in the closure of the fore arc basin and is then blocked. The PSP fails at the opposite side of the Luzon arc along the westward dipping fault. The failure releases lithospheric compression in this region and results in the initiation of southward-propagating subduction of the PSP under northeastern Taiwan. The incipient subduction zone becomes part of the southeastward-retreating Ryukyu subduction zone, which allows the Okinawa back arc rift to propagate into Taiwan. The Taiwan collision thus includes the following succession of major processes over time, or from south to north: (1) an L-W shortening of the PSP in the Luzon arc; (2) a failure of this plate at the western side of the arc and the formation of the eastward-dipping Longitudinal Valley Fault (the transient plate boundary); O) a closure of the fore arc basin and a rapid uplift of the orogen; i4) a failure of the PSP at the eastern side of the Luzon arc partly overthrusting the orogen, and the initiation of westward (WN-ward) subduction of the PSP; (5) and finally 'back arc' rifting in the rear of this incipient subduction zone (i.e. in northern Taiwan). All these processes commence with some delay with respect to the preceding ones and propagate southwards.