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Chemical composition of phyllosilicates, amphiboles and carbonates from hydrothermally altered granitoid and metamorphic rocks in the Pezinok–Kolársky vrch Hill Sb–Au deposit, Western Carpathians, Slovakia
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
Chlorite replacing biotite (phlogophite and annite) and amphibole (hornblende, tschermakite and edenite). Fe2+-clinochlore is a dominant type of chlorite. Muscovite and illite–carbonate / carbonate–sulphides zones are superimposed on the chlorite zone. Hydrothermal phengitic muscovite replaces plagioclase and chlorite. In the innermost zone, carbonates and sulphides become abundant, muscovite and feldspars are replaced by illite. Carbonates (ankerite and dolomite) replacing amphibole and plagioclase.
Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia
Published in Australian Journal of Earth Sciences, 2023
B. R. Hines, D. Turnbull, L. Ashworth, S. McKnight
Microcline occurs in subordinate to equal proportions with albite, and a weak spatial trend is apparent in the distribution of feldspars; the proportion of microcline is greater in dykes in the western Dorchap Range, with the proportion of albite increasing and microcline abruptly decreasing eastwards. Similarly, from the small sample set at Glen Wills, the microcline is dominant in the northernmost pegmatites, but abruptly diminishes to the south. Quartz, albite, microcline and muscovite account for >85% of the mineral composition in almost all (86%) of the pegmatites analysed by XRD. Furthermore, XRD results indicate that spodumene is the principal Li mineral in the Dorchap Range (Figure 8), except for the Boones and Holloway dykes (Figure 2), which are dominated by petalite, and the Rhoda Spur dyke where amblygonite is the primary Li phase. Subordinate amblygonite is also associated with the Boones and Gosport dykes; likewise, cookeite occurs in the Gosport and Eagle dykes. The Glen Wills pegmatites differ from the northern Dorchap Range dykes in that their primary Li-bearing phases are lepidolite, amblygonite and cookeite. In addition, trace amounts of dravite, Cs–Li beryl, clinochlore and the annite–biotite–phlogopite series (Table 1) were also identified by XRD analysis of pegmatites in the Dorchap Dyke Swarm.
The Use of Mining Tailings as Analog of Rare Earth Elements Resources: Part 1 – Characterization and Preliminary Separation
Published in Mineral Processing and Extractive Metallurgy Review, 2022
George Blankson Abaka-Wood, Jonas Addai-Mensah, William Skinner
Mineral mass abundance of the identified phases has been presented in Table 7. The results suggest that both tailings have similar mineralogical compositions. For example, the data indicate that both tailings mainly contain silicate gangue minerals, including quartz, illite, muscovite, annite, and feldspar, and iron oxides, including hematite-magnetite and goethite-limonite associations. However, there are variable concentrations of each mineral phases; for example, CFRT has higher iron oxides concentration than BRFT, which validates the assertion made in Section 3.3.1. The iron oxides content in both tailings is higher than that of silicate minerals. Furthermore, the results also show that REE minerals identified include bastnäsite [Ce, La, Y(CO3)F], monazite [(Ce, La)PO4], and stetindite [CeSiO4]. Bastnäsite was detected more consistently and in higher abundance than all the other REE minerals as depicted in Table 7 and Figure 7. Stillwellite, brannerite, and florencite were in trace amounts in both tailings.
The “intraorogenic” Svecofennian Herräng mafic dyke swarm in east-central Sweden: age, geochemistry and tectonic significance
Published in GFF, 2020
Åke Johansson, Andreas Karlsson
Biotite in sample ÅJ14:01 (Limnaren) usually have a fresh core, with a thin rim (max. 10 µm) of chlorite. The cores show Mg# of 0.56 (n = 3) and concentrations of Al above 1 a.p.f.u, and can be classified as phlogopite (Rieder et al. 1998). Biotite in sample ÅJ14:10 (Herräng) has the lowest average Mg# of 0.45 (n = 3), but is usually unaltered, and straddles the compositional border between phlogopite and annite. Biotite in sample ÅJ14:16 (Fogdö) shows the most variable compositions, from Al-rich to Al-poor (all still above 1 a.p.f.u), with Mg# between 0.52 and 0.55 (n = 7). These phlogopites generally have a very fine rim of chlorite (~1 µm), but apart from that they are generally unaltered. All analyzed biotites have elevated aluminum contents and trend slightly towards siderophyllite/eastonite, although they are still within the annite-phlogopite compositional fields (Online Appendix 2C).