3 resultados para Special Libraries Association

em Aston University Research Archive


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Cultural institutions in the UK are repositories of a wealth of historical material. The scholarly importance of such resources is at the basis of the numerous digitisation projects aimed at widening their access worldwide. The lack of national policies has left those institutions alone in engaging in dissemination activities and in raising awareness of their own online material. Of particular interest to the author are the digital special collections hosted in the English Universities. The main activities of these institutions differ from others, such as museums, archives and public libraries, as they do not have the main institutional duties of preserving and the exploiting of their holdings. This article highlights related issues and suggests some of the possible measures to effectively promote and disseminate universities’ online digital special collections.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Cultural institutions in the UK are repositories of a wealth of historical material. The scholarly importance of such resources is at the basis of the numerous digitisation projects aimed at widening their access worldwide. The lack of national policies has left those institutions alone in engaging in dissemination activities and in raising awareness of their own online material. Of particular interest to the author are the digital special collections hosted in the English Universities. The main activities of these institutions differ from others, such as museums, archives and public libraries, as they do not have the main institutional duties of preserving and the exploiting of their holdings. This article highlights related issues and suggests some of the possible measures to effectively promote and disseminate universities’ online digital special collections.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Two aspects of gold mineralisation in the Caledonides of the British Isles have been investigated: gold-telluride mineralisation at Clogau Mine, North Wales; and placer gold mineralisation in the Southern Uplands, Scotland. The primary ore assemblage at Clogau Mine is pyrite, arsenopyrite, cobaltite, pyrrhotine, chalcopyrite, galena, tellurbismuth, tetradymite, altaite, hessite, native gold, wehrlite, hedleyite, native bismuth, bismuthunite and various sulphosalts. The generalised paragenesis is early Fe, Co, Cu, As and S species, and later minerals of Pb, Bi, Ag, Au, Te, Sb. Electron probe micro-analysis (EPMA) of complex telluride-sulphide intergrowths suggests that these intergrowths formed by co-crystallisation/replacement processes and not exsolution. Minor element chemical variation, in the sulphides and tellurides, indicates that antimony and cadmium are preferentially partitioned into telluride minerals. Mineral stability diagrams suggest that during gold deposition log bf aTe2 was between -7.9 and -9.7 and log bf aS2 between -12.4 and -13.8. Co-existing mineral assemblages indicate that the final stages of telluride mineralisation were between c. 250 - 275oC. It is suggested that the high-grade telluride ore shoot was the result of remobilisation of Au, Bi, Ag and Te from low grade mineralisation elsewhere within the vein system, and that gold deposition was brought about by destabilisation of gold chloride complexes by interaction with graphite, sulphides and tellurbismuth. Scanning electron microscopy of planer gold grains from the Southern Uplands, Scotland, indicates that detailed studies on the morphology of placer gold can be used to elucidate the history of gold in the placer environment. In total 18 different morphological characteristics were identified. These were divided on an empirical basis, using the relative degree of mechanical attrition, into proximal and distal characteristics. One morphological characteristic (a porous/spongy surface at high magnification) is considered to be chemical in origin and represent the growth of `new' gold in the placer environment. The geographical distribution of morphological characteristics has been examined and suggests that proximal placer gold is spatially associated with the Loch Doon, Cairsphairn and Fleet granitoids. Quantitative EPMA of the placer gold reveals two compositional populations of placer gold. Examination of the geographical distribution of fineness suggests a loose spatial association between granitoids and low fineness placer gold. Also identified was chemically heterogeneous placer gold. EPMA studies of these heterogeneities allowed estimation of annealing history limits, which suggest that the heterogeneities formed between 150 and 235oC. It is concluded, on the basis of relationships between morphology and composition, that there are two types of placer gold in the Southern Uplands: (i) placer gold which is directly inherited from a hypogene source probably spatially associated with granitoids; and (ii) placer gold that has formed during supergene processes.