Reflected-light microscopy of uraniferous bitumens

1992 ◽  
Vol 56 (382) ◽  
pp. 85-99 ◽  
Author(s):  
P. A. Eakin ◽  
A. P. Gize
Keyword(s):  
South Africa ◽  
Great Britain ◽  
Light Microscopy ◽  
Mechanical Deformation ◽  
Mineral Inclusion ◽  
Reduction Reactions ◽  
Reflected Light ◽  
Reduction Mechanisms ◽  
High Concentrations ◽  
Early Alteration

AbstractUraniferous bitumens from Great Britain, Scandinavia and South Africa have been studied by oilimmersion reflected-light microscopy and categorised into those formed either by replacement of preexisting uraninite and pitchblende or by complexation/reduction mechanisms in pre-existing hydrocarbons. The former are characterised by displaying normal replacive textures, and containing high concentrations of non-mineral-bound uranium, or later, occasionally exotic, uraniferous fracturefilling phases. Uraniferous bitumens formed during complexation/reduction reactions display monotonous mineralogies and ordered mineral-inclusion distributions.Radiolytic alteration of uraniferous bitumens induces both chemical and mechanical alteration. Early alteration is marked by the generation of mobile hydrocarbons during 'cracking reactions' with subsequent within-sample migration to form globular bitumens and dendritic interspersions of mineralrich and -poor uraniferous bitumen. Mobile hydrocarbons may act as lubricants during mechanical deformation. Advanced organic alteration is characterised by well-documented increased reflectance around uraniferous grains, and by fracturing of the bitumens.

scholarly journals Ore Microscopy of the Pegmatites of Keffi Area, North Central Nigeria

2021 ◽  
Vol 2 (5) ◽  
pp. 34-40
Author(s):  
I. Y. Tanko ◽  
K. Dzigbodi-Adjimah
Keyword(s):  
Quantitative Analysis ◽  
Light Microscopy ◽  
Elemental Composition ◽  
North Central ◽  
Wavelength Dispersive Spectrometry ◽  
Reflected Light ◽  
Ore Minerals ◽  
Backscattered Electron ◽  
High Concentrations ◽  
Area North

Investigation of the pegmatites of Keffi area was carried out in reflected light microscopy to determine the texture, elemental composition, and the semi-quantitative analysis of the ore minerals from the three groups of pegmatites identified in Keffi area: the non-mineralised, the intermediate and the mineralised pegmatites. Backscattered Electron (BSE) images and Wavelength Dispersive Spectrometry (WDS) were used. Petrographically the portion which is characterised by profuse albitisation, sericitisation and silicification is also associated with the development of cleavelandite, lepidolite, coloured tourmaline and high concentrations of cassiterite and columbite-tantalite (coltan).The order of crystallisation in the pegmatites is from microcline to quartz followed by (plagioclases) oligoclase to albite and by mica (from biotite to muscovite) then by accessory minerals such as black tourmaline, garnet, beryl and lastly oxides of Sn-Nb-Ta. Sphene, rutile, zircon, apatite, ilmenite, and magnetite appeared to be earliest minerals whilst garnet pyrite and chalcopyrite may be syn-metamorphic. Beryl and coloured tourmaline appear to be of hydrothermal phase.

Mineralization at Seathwaite Tam, near Coniston, English Lake District: The first occurrence of wittichenite in Great Britain

1979 ◽  
Vol 43 (325) ◽  
pp. 103-107 ◽  
Author(s):  
C. J. Stanley ◽  
A. J. Criddle
Keyword(s):  
Great Britain ◽  
Light Microscopy ◽  
Polished Section ◽  
Lake District ◽  
Ore Genesis ◽  
Copper Mine ◽  
Mineral Paragenesis ◽  
Reflected Light ◽  
English Lake District ◽  
First Occurrence

SummaryOre specimens from the abandoned copper mine at Seathwaite Tarn, Cumbria, were studied in polished section by reflected light microscopy. The mineral paragenesis is described and related to current views on Lake District ore genesis. A common origin with the neighbouring deposit at Coniston is proposed. Wittichenite was identified in the ore, and is the first authenticated occurrence in Great Britain.

Tandem scanning reflected light microscopy: How it works and applications

1986 ◽  
Vol 44 ◽  
pp. 84-87
Author(s):  
Alan Boyde ◽  
Milan Hadravský ◽  
Mojmír Petran ◽  
Timothy F. Watson ◽  
Sheila J. Jones ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Focal Plane ◽  
Central Symmetry ◽  
Single Line ◽  
Scanning Microscope ◽  
Reflected Light ◽  
Illuminating Light ◽  
Illuminating Beam

The principles of tandem scanning reflected light microscopy and the design of recent instruments are fully described elsewhere and here only briefly. The illuminating light is intercepted by a rotating aperture disc which lies in the intermediate focal plane of a standard LM objective. This device provides an array of separate scanning beams which light up corresponding patches in the plane of focus more intensely than out of focus layers. Reflected light from these patches is imaged on to a matching array of apertures on the opposite side of the same aperture disc and which are scanning in the focal plane of the eyepiece. An arrangement of mirrors converts the central symmetry of the disc into congruency, so that the array of apertures which chop the illuminating beam is identical with the array on the observation side. Thus both illumination and “detection” are scanned in tandem, giving rise to the name Tandem Scanning Microscope (TSM). The apertures are arranged on Archimedean spirals: each opposed pair scans a single line in the image.

Defects of Planarity of Carbon Films Supported on Electron Microscope Grids Revealed by Reflected Light Microscopy

1994 ◽  
Vol 112 (3) ◽  
pp. 252-258 ◽  
Author(s):  
Marc Schmutz ◽  
Jacques Lang ◽  
Sabine Graff ◽  
Alain Brisson
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Carbon Films ◽  
Reflected Light

Hyperspectral reflected light microscopy of plasmonic Au/Ag alloy nanoparticles incubated as multiplex chromatic biomarkers with cancer cells

The Analyst ◽  
2014 ◽  
Vol 139 (20) ◽  
pp. 5247-5253 ◽  
Author(s):  
Sergiy Patskovsky ◽  
Eric Bergeron ◽  
David Rioux ◽  
Mikaël Simard ◽  
Michel Meunier
Keyword(s):  
Light Microscopy ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Human Cancer ◽  
Spatial Localization ◽  
Alloy Nanoparticles ◽  
Human Cancer Cell ◽  
Plasmonic Nanoparticle ◽  
Reflected Light ◽  
Spectroscopic Identification

We report a hyperspectral reflected light microscopy system for plasmonic nanoparticle (NP) imaging, and compare with a conventional darkfield method for spatial localization and spectroscopic identification of single Au, Ag and Au/Ag alloy NPs incubated with fixed human cancer cell preparations.

Ein föderales Imperium?

2021 ◽  
Author(s):  
Patrick Rummel
Keyword(s):  
South Africa ◽  
New Zealand ◽  
Great Britain ◽  
British Empire ◽  
19Th Century ◽  
Military Personnel ◽  
The Other ◽  
The 19Th Century

The previously ignored model of Greek colonisation attracted numerous actors from the 19th century British empire: historians, politicians, administrators, military personnel, journalists or anonymous commentators used the ancient paradigm to advocate a global federation exclusively encompassing Great Britain and the settler colonies in Canada, Australia, New Zealand and South Africa. Unlike other historical templates, Greek colonisation could be viewed as innovative and unspent: innovative because of the possibility of combining empire and liberty and unspent due to its very novelty, which did not contain the ‘imperial vice’ the other models had so often shown and which had always led to their political and cultural decline.

Chaetomium strumarium. [Descriptions of Fungi and Bacteria].

2006 ◽  
Author(s):  
D. W. Minter
Keyword(s):  
South Africa ◽  
Saudi Arabia ◽  
Great Britain ◽  
The Netherlands ◽  
Host Range ◽  
Geographical Distribution ◽  
Canary Islands ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Horticultural Crops

Abstract C. strumarium is described and illustrated. Information on diseases caused by C. strumarium, host range (field and horticultural crops, trees, dung, man and artefacts), geographical distribution (Algeria, Canary Islands, Democratic Republic of Congo, Egypt, Gambia, Kenya, Namibia, Nigeria, South Africa, Tanzania, USA, India, Nepal, Pakistan, Thailand, Western Australia, Germany, Great Britain, the Netherlands, Cyprus, Israel, Kuwait and Saudi Arabia), and transmission is provided.

Septoria antirrhini. [Descriptions of Fungi and Bacteria].

2004 ◽  
Author(s):  
T. V. Andrianova
Keyword(s):  
South Africa ◽  
Czech Republic ◽  
New Zealand ◽  
Great Britain ◽  
South America ◽  
Geographical Distribution ◽  
Infected Plant ◽  
Weather Conditions ◽  
Plant Debris ◽  
Wet Weather

Abstract A description is provided for Septoria antirrhini. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Leaf spot, leaf drying, defoliation. HOSTS: Antirrhinum antirrhiniflorum, A. majus, A. siculum (Scrophulariaceae). GEOGRAPHICAL DISTRIBUTION: AFRICA: South Africa. NORTH AMERICA: Canada, USA. SOUTH AMERICA: Chile, Colombia. ASIA: Armenia, Azerbaijan, China, Iran, Israel. AUSTRALASIA: Australia, New Zealand. EUROPE: Bulgaria, Czech Republic, Estonia, France, Germany, Great Britain, Hungary, Ireland, Italy, Netherlands, Portugal, Romania, Ukraine, former Yugoslavia. TRANSMISSION: Not reported, but almost certainly by airborne, splash-dispersed conidia from infected plant debris and seed stocks. The disease is significantly more severe under wet weather conditions (SINADSKIY et al., 1985).

scholarly journals Palaeoclimates: the first two billion years

2006 ◽  
Vol 361 (1470) ◽  
pp. 917-929 ◽  
Author(s):  
James F Kasting ◽  
Shuhei Ono
Keyword(s):  
South Africa ◽  
Oxygen Isotopes ◽  
Natural Explanation ◽  
Witwatersrand Basin ◽  
Late Archaean ◽  
Bacterial Sulphate Reduction ◽  
Climatic Constraints ◽  
The Mean ◽  
High Concentrations ◽  
Earth’S Climate

Earth's climate during the Archaean remains highly uncertain, as the relevant geologic evidence is sparse and occasionally contradictory. Oxygen isotopes in cherts suggest that between 3.5 and 3.2 Gyr ago (Ga) the Archaean climate was hot (55–85 °C); however, the fact that these cherts have experienced only a modest amount of weathering suggests that the climate was temperate, as today. The presence of diamictites in the Pongola Supergroup and the Witwatersrand Basin of South Africa suggests that by 2.9 Ga the climate was glacial. The Late Archaean was relatively warm; then glaciation (possibly of global extent) reappeared in the Early Palaeoproterozoic, around 2.3–2.4 Ga. Fitting these climatic constraints with a model requires high concentrations of atmospheric CO 2 or CH 4 , or both. Solar luminosity was 20–25% lower than today, so elevated greenhouse gas concentrations were needed just to keep the mean surface temperature above freezing. A rise in O 2 at approximately 2.4 Ga, and a concomitant decrease in CH 4 , provides a natural explanation for the Palaeoproterozoic glaciations. The Mid-Archaean glaciations may have been caused by a drawdown in H 2 and CH 4 caused by the origin of bacterial sulphate reduction. More work is needed to test this latter hypothesis.

Chaetomium elatum. [Descriptions of Fungi and Bacteria].

2006 ◽  
Author(s):  
D. W. Minter
Keyword(s):  
South Africa ◽  
New York ◽  
New Mexico ◽  
Great Britain ◽  
New South ◽  
Conservation Status ◽  
Washington Dc ◽  
Horticultural Crops ◽  
South Wales ◽  
Chaetomium Elatum

Abstract C. elatum is described and illustrated. Information on host range (mainly field and horticultural crops, trees, wood, nematode, dung and artefacts), geographical distribution (South Africa; Manitoba, Ontario and Saskatchewan, Canada; California, Kansas, Louisiana, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania and Washington DC, USA; Chile; Ecuador; Venezuela; Gansu and Jiangsu, China; India; Pakistan; Philippines; Japan; Russia; Turkey; Uzbekistan; New South Wales, Victoria and Western Australia; New Zealand; Dominican Republic; Austria; Belgium; Croatia; Czech Republic; Denmark; France; Germany; Great Britain; Greece; Hungary; Ireland; Italy; Netherlands; Poland; Romania; Russia; Sweden; Switzerland; Ukraine; Cyprus; Iraq; and Kuwait), biology, and conservation status is presented.

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