The new minerals manganvesuviante and tweddillite, both formed by hydrothermal alteration of primary manganese ores, are described from the Kalahari manganese fields (Republic of South Africa). In addition, single-crystal X-ray structure refinements of both new minerals are presented.Manganvesuvianite is a tetragonal vesuvianite mineral with the simplified formula Ca 19 Mn 3+ (Al,Mn 3+ ,Fe 3+ ) 10 (Mg,Mn 2+ ) 2 Si 18 O 69 (OH) 9 , characterized by Mn 3+ occupying the fivecoordinated position (square pyramid). The crystals have simple prismatic forms: {100}, {110} terminated by {101} and exhibit deep maroon red colour. With polarized light the crystals are strongly pleochroic, yellowish parallel to E and dark red to lilac parallel to O.Tweddillite is an epidote-group mineral (space group space group P2 1 /m, a = 8.932(5), b = 5.698(4), c = 10.310(5) A Ê , b = 114.56(4), V = 477.3(8) A Ê 3 ) with the simplified formula CaSr(Mn 3+ ,Fe 3+ ) 2 Al [Si 3 O 12 ](OH), closely related to strontiopiemontite. The difference between strontiopiemontite and tweddillite is the concentration of octahedral Mn 3+ . Strontiopiemontite has Mn 3+ mainly on the M3 site whereas tweddillite has Mn 3+ with minor Fe 3+ on M3 and M1. Tweddillite forms aggregates of very thin dark red {001} blades characterized by striking pleochroism. The crystals appear dark red parallel to b and orange-yellow parallel to a. Perpendicular to (001) the blades appear magenta to red.

The morphology and mineral chemistry of gold and associated sulphides at Sheba, Fairview, and New Consort gold mines in the Barberton Greenstone Belt (BGB) identify two main types of mineralization. The first type occurs associated with sulphides (mainly pyrite), either as inclusions (10-30 µm) or as sub-microscopic gold. The second gold type consists of large gold grains (≥ 100µm) within the silicates (mostly quartz).LA-ICP-MS studies reveal that some gold and associated sulphide grains contain high values of Cl, Br, Na, and I.The elemental relationships reflect the different chemistry and precipitation processes of possible source fluids, and identify several episodes of mineralisation in the study area, one of them formed due to a boiling process in a supercritical hydrothermal environment. This paper reports on the compositional characteristics of these gold grains, the significance of the halogen contents, and the implications for possible sources of the gold and associated sulphides.

a b s t r a c tThe disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC Â GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non-ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC Â GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC Â GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination.

The identification of gold-bearing material is essential for combating the theft of gold in South Africa. Material seized in police operations is generally a mixture of gold from different mines, and as such cannot be traced back to a single location. ICP-OES analysis of material dissolved by acid dissolution provided a database of gold compositions comprising gold from South African mines, illegal gold stolen from the mines, and commercial gold alloys and jewelery. Discrimination between legal and illegal gold was possible due to the presence of Pb, As, Sb, Sn, Se, and Te in the stolen material, elements which are not present in legally produced gold. The presence of these elements is a quick and simple way to distinguish between gold alloys based on refined gold, such as in commercially manufactured jewelery, and gold alloys containing a proportion of unrefined and therefore illegally obtained gold.Gold lost from mining operations due to theft in South Africa makes up for a large volume of the total production value [1,2]. Anything from the ore to the final metal product is stolen and the challenge is to develop techniques like elemental profiling to identify the original source of the gold, despite different beneficiation procedures applied by companies and criminal syndicates. The mineralogy of gold ores from the Witwatersrand mines is relatively consistent and the recovery of the gold is easily achieved with unsophisticated methods, such as panning, amalgamation, and cyanidation [3,4].The trace element profiles of substances such as paint [5,6], glass [7,8] and precious metals [9] have been used to prove a link between a sample of the material in question and samples from known provenance. There have been problems with the interpretation of the results of such profiling [10], and this has been extensively discussed and reviewed in the literature [11]. Using such a database, which is representative of the population(s), should enable the attribution of the type and source of such material on a scientific basis, without having to worry about the terms -unique‖ or -identification‖ [12], and should produce results which have more weight when presented in court [13,14]. It has been shown that samples from the same source show significant uniformity in trace element distribution, and significant variation between different sources, leading to good discrimination between sources [15,16].

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