The manner of occurrence of sulphides (pyrite and pyrite melnikovite?) in a number of samples from the Philippine Sea is described and their genesis briefly discussed. Polished sections of consolidated material revealed both shards of volcanic glass and pyritized remains of microorganisms (Radiolaria?) in a pyrite matrix with a mosaic texture. The mosaic texture is thought to be due to early sy...

An increasing number of studies constrain the importance of iron for the long-term retention of phosphorus (P) under anoxic conditions, i.e. the formation of reduced iron phosphate minerals such as vivianite (Fe3(PO4)2⋅8H2O). Much remains unknown about vivianite formation, the factors controlling its occurrence, and its relevance for P burial during early sediment diagenesis. To study the occur...

Copper, uranium, and rare earth element (REE) mineralisation occurs in hydrocarbon-bearing Devonian continental sandstones southwest Orkney, Scotland. The aeolian Yesnaby Sandstone Formation fluvial Harra Ebb were mineralised following oil emplacement. REE-bearing APS mineral florencite is particularly associated with bituminous nodules, many of which contain brannerite. Subsequently hydrotherm...

The Ascutita porphyry Cu-Mo prospect is located in the SW Poiana Rusca Mountains, Romania. Current assessment estimates a resource of 110 Mt @ 0.15 % Cu-equivalent. In relatively low-grade deposits such as this, by-products Ag (2–3 ppm) are important determining economic feasibility overall orebody. Assayed Cu and have clear downhole correlation. absence other silver-bearing minerals, or correl...

are important factors in the elicitation of contact dermatitis. Our current data show that patients with a history of using temporary black henna tattoos are often highly sensitized to PPD after exposure to such high concentrations and require only very low concentrations of PPD for elicitation of an allergic response. As the current practice of using PPD 1% pet. often results in unacceptably s...

The origin in rocks of the common iron sulphides, pyrrhotine, Fe 1 xS and pyrite, FeS2 and their behaviour during geochemical processes is best considered using the simplified redox reaction: 2FeS ~-~ FeS2 + Fe 2 + + 2e . Thus pyrrhotine is more reduced than pyrite and is the stable iron sulphide formed from magmas except where relatively high oxygen fugacities result from falling pressure or h...

Previous investigations suggested that sulphide layers on pure silver surfaces were easily removed with a reducing plasma afterglow at atmospheric pressure, but harder to remove silver-copper alloys. In this study we investigated by synchrotron x-ray photoelectron spectroscopy the effect of tarnished silver, copper and sterling alloy. The results confirmed was able reduce in depth all sulphides...