Iron plus magnesium-bearing beryl from granitic pegmatites: an EMPA, LA-ICP-MS, Mossbauer spectroscopy, and powder XRD study
| Authors | |
|---|---|
| Year of publication | 2014 |
| Type | Article in Periodical |
| Magazine / Source | Canadian Mineralogist |
| MU Faculty or unit | |
| Citation | |
| Field | Geology and mineralogy |
| Keywords | beryl; iron; magnesium; EMPA; LA-ICP-MS; Mossbauer spectroscopy; granitic pegmatites |
| Description | Five samples of blue, bluish green, and green Fe,Mg-enriched beryl from Li-poor granitic pegmatites [beryl-columbite (LCT) pegmatites at Kovarova and Bonenov in the Czech Republic and Val Sissone in Italy; a primitive pegmatite at Beryller, Untersulzbachtal, Austria; and a euxenite (NYF) pegmatite from the Beryl Pit, Quadeville, Ontario] were investigated using EMPA, Mossbauer spectroscopy, LA-ICP-MS, and powder XRD diffraction. The EMPA data show highly heterogeneous (Kovarova, Val Sissone) to rather homogeneous crystals (Bonenov, Beryller, Quadeville), with high variations in Al (1.51-1.91 apfu), Mg (0.01-0.31), Fe-tot (0.01-0.18), and Na (0.04-0.37). The substitution (CH)square + R-O(3+) <-> R-CH(+) + R-O(2+) is dominant and supported by the powder XRD data. LA-ICP-MS revealed notable concentrations of some trace elements: Cs <= 7568 ppm (Kovarova), Li <= 928 ppm (Quadeville), Sc <= 2823 ppm (Val Sissone). Beryl samples have mostly comparable contents of Fe3+, similar to 25% at the O-site, but differ in the presence of Fe2+ at the T(2)-site. Primitive characteristics of some examined beryl (Mg/(Mg+Fe-tot) = 0.37-0.68 reflect low degree of fractionation of the host pegmatite (Beryller), or high degree of Mg-contamination from host metabasites in the pegmatite dikes (Kovarova, Bonenov). The concentrations and ratios of selected elements, including Fe3+/Fe2+, in beryl from these Li-poor pegmatites are not feasible for any implications of pegmatite-family affinity or degree of its fractionation except for Li; however, no evident correlation between Li and Cs contents was found. |
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