Publication details

Topaz as an important host for Ge in granites and greisens

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Year of publication 2013
Type Article in Periodical
Magazine / Source Mineralogical Magazine
MU Faculty or unit

Faculty of Science

Field Analytic chemistry
Keywords topaz; germanium; gallium; LA-ICP-MS; Krusne Hory Mts.; Erzgebirge
Description The composition of topaz from different granites and greisen in the Krusne Hory/Erzgebirge area was investigated using electron microprobe analysis (EMPA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). All topaz grains are rich in F (17.9-19.8 wt.%, 1.73-1.90 a.p.f.u.) and the most important minor/trace elements are P, Ge and Ga. Contents of P up to 1 wt.% P2O5 (0.025 a.p.f.u.) were found in topaz from the strongly peraluminous P-rich magmatic systems at Podlesi. Regardless of genetic type, topaz from granites typically contains 50-100 ppm Ge. The greatest amounts (up to 204 ppm Ge) were found in topaz from quartz-topaz-apatite greisen in Krasno. In fractionated granites and greisens, topaz is calculated to contain 23-87% of the bulk Ge content in the rock. In contrast, topaz does not concentrate Ga. The Ga content of topaz (typically 5-35 ppm in S-type granites, <10 ppm Ga in A-type granites) is usually smaller than the bulk Ga content of the rock. In addition, up to 16 ppm Sc, 23 ppm Sn and >400 ppm Fe may be present.
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