...Cristian Biagioni; Elena Bonaccorsi; Stefano Merlino; Danilo Bersani; Claudia Forte Abstract X-ray diffraction studies of “tobermorite 10 Å”, obtained through heating of the “anomalous” tobermorite 11 Å from N’Chwaning II mine (Kalahari Manganese Field, RSA), show the widespread structural disorder...

... differ in their behaviour upon heating, which can be “normal” if they collapse to form a 9 Å phase or “anomalous” if they preserve their original basal spacing. The “anomalous” thermal behaviour of tobermorite 11 Å from N’Chwaning II mine (Kalahari Manganese Field, Republic of South Africa), which does...

... y Si 6– y )O 15+2 x – y ·5H 2 O. Its endmember compositions correspond to tobermorite Ca 5 Si 6 O 17 ·5H 2 O ( x = 1 and y = 0) and the new species kenotobermorite, Ca 4 Si 6 O 15 (OH) 2 ·5H 2 O ( x = 0 and y = 0). The type locality of kenotobermorite is the N'Chwaning II mine, Kalahari Manganese...

...P. Bonazzi; L. Bindi; O. Medenbach; R. Pagano; G. I. Lampronti; S. Menchetti Abstract Olmiite, ideally CaMn[SiO 3 (OH)](OH), is a newly identified mineral from the N’Chwaning II mine of the Kalahari manganese fields (Republic of South Africa), which occurs as a product of hydrothermal alteration...

... ) VIII (Mn 1.95 Fe 0.01 Al 0.04 ) VI [SiO 4 ] 2.07 [H 4 O 4 ] 0.93 from the N’Chwaning II mine at the Kalahari manganese fields, Republic of South Africa, has been studied by single-crystal X-ray diffraction at 100 and 293 K at ambient pressure and up to 8.7 GPa in a diamond-anvil cell at 293 K...

...B. Cairncross; H. Tsikos; C. Harris Abstract Prehnite is described herein from the N’Chwaning II mine, Kalahari manganese field for the first time. The habit and composition are atypical for the species. The mineral occurs as elongated, prismatic orthorhombic yellow-orange crystals arranged...

... vesuvianite, a = 15.487(2), c = 11.764(2) Å from the N’chwaning II mine of the Kalahari manganese fields (RSA). This untwinned crystal has Cu 2+ and Mn 2+ , Mn 3+ forming the square pyramid and exhibits an acentric ordering pattern with 85% string A and 15% string B. This is compared to a reinvestigation...

...Thomas Armbruster; Edwin Gnos Abstract Strongly zoned Mn-rich vesuvianites with MnO concentrations up to 14.3 wt% from the N’chwaning II mine of the Kalahari manganese field (South Africa) crystallized at hydrothermal conditions below 450 °C. These vesuvianites are by far the most Mn-rich samples...

...Fig. 2 Bunch of lath-shaped crystals of oyelite. N’Chwaning II mine, Kalahari, South Africa. Scanning electron microscope secondary-electron image. ...

...F ig . 2. Polarized optical absorption single-crystal spectra of the close to end-member henritermierite (sample #97) from the N’Chwaning II mine. Positions ν 1 –ν 4 indicate band peaks and shoulders. The absorber thickness was 19 μm. ...

... with calcite, bultfonteinite, and chlorite at N’chwaning mine, located in the Kalahari manganese field, northern Cape Province, South Africa. The aggregates consist of light brown, transparent needles, which average 1.0 x 0.1 x 0.05 mm in size. Nchwaningite is named after the mine N’chwaning II, where...

...: olivine (Mg, Si), albite (Na, Al, Si), orthoclase (K, Al, Si), and diopside (Ca, Mg, Si). In order to check for the reliability of chemical analyses, a crystal of kenotobermorite from the N’Chwaning II mine, Republic of South Africa, Ca 4 Si 6 O 15 (OH) 2 · 5H 2 O, having a well-defined (Ca:Si) atomic...

... at the N’chwaning II mine, turned later into a M.Sc. thesis that was completed under the guidance of Bernd Lehmann in Clausthal. Following my graduation I took up Nic’s offer to return to South Africa to expand on the preliminary results towards a Ph.D. degree in geology. Detailed mineralogical and geochemical...

... by hydrothermal alteration of primary Mn ores at the Wessels and N’Chwaning II mines in the Kalahari manganese field of South Africa. At the N’Chwaning II mine the mineral is also rock-forming and is associated with grossular, xonotlite, and calcite in calc-silicate lenses. Type material (N’Chwaning II...

... is manganvesuvianite. Crystal structure analysis of manganvesuvianite indicates that Mn 3+ occupies the five-coordinated square pyramidal Y ′ position leading to Jahn-Teller distortion where the four-fold axis of the square pyramid is elongated. Manganvesuvianite (Wessels mine and N’Chwaning II mine...