Crystal chemistry of natural Pb-rich tourmalines
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| Year of publication | 2021 |
| Type | Conference abstract |
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| Description | Lead is one of the cations with a large ionic radius (1.35 A) and should therefore enter the tourmaline structure as a divalent cation Pb2+ at the nine-coordinated X-site. The lead contents typically found in tourmaline are between tens and hundreds of ppm. The observed paragenetic relationships indicate that the Pb-enrichment in tourmaline is related to both albitization of amazonite (in Minh Tien) and its hydrothermal alteration (all studied localities). Formation of Pb-rich tourmaline is not restricted to Ca-rich systems (and Pb- Ca-1 exchange) and takes place also in Na,Li,F-rich tourmalines. Hydrothermal tourmalines may locally reach compositions dominated by the theoretical Pb-analogue of fluor-liddicoatite. |
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