 | | Journal (article/letter/editorial) | | tourmalinites of the Duruchaus Formation of central Namibia reveal a common compositional trend that occurs...follow this trend Fe3þ along a join between ‘‘oxy-dravite’’ [Na(Mg2Al)(Al6)(Si6O18)(BO3)3(OH)3(O)] and...more magnesian and fall close to the dravite and ‘‘oxy-dravite’’ compositions. These latter tourmaline...tourmaline, mineral chemistry, tourmalinites, Namibia, evaporite, magnesian. Introduction The pioneering...Formation of the Damara Orogenic Belt in central Namibia are of special interest because they contain well-preserved |  | | Journal (article/letter/editorial) | | Na, Fe 3+ and WO, and follow a trend between “oxy-dravite” and povondraite (O–P trend). This compositional...Species (X) (Y3) Alkali group Schorl Oxy-schorl Dravite “Oxy-dravite”a Povondraite Na Na Na Na Na X-site... The tourmaline species generated are dravite and “oxy-dravite” at high Na (and Cl) in the fluids and...Paleozoic sedimentary rocks from the Appalachian region (Henry et al., 1994; Krynine, 1946) and Switzerland...were considered to be elbaite, dravite, schorl, uvite and chromium dravite (e.g. Krynine, 1946; Srivastava |  | | Journal (article/letter/editorial) | | Eu/Eu* ¼ 058 6 003). Tourmaline is dravite and/or ‘oxy-dravite’ with a tendency to povondraite, showing...studied samples are (Febearing) dravites and/or ‘oxy-dravites’ with a trend to povondraite, based on the...Tourmaline (based on 245 anions); dravites and/or ‘oxy-dravites’ Sample: AI-2 AI-3 rim III rim II rim...indicated (Fig. 9c). The data plot parallel to the ‘oxy-dravite–povondraite’ join and therefore the FeAl–1/AlO[R(OH)]–1...FeAl–1/AlO[R(OH)]–1 exchange, but with a tendency to dravite (Fig. 9d). For the large tourmaline shown in Fig |
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