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Concentration of feldspar from trachyte
Published in Gülhan Özbayoğlu, Çetin Hoşten, M. Ümit Atalay, Cahit Hiçyılmaz, A. İhsan Arol, Mineral Processing on the Verge of the 21st Century, 2017
Trachytes are also alternative source of feldspar. They are composed of alkali feldspars such as sanidine (in the majority), anorthoclase, or in the more sodic types oligoclase or albite, ferromagnesian minerals such as biotite, hornblend or pyroxene, and accessory minerals such as zircon, ilmenite, apatite and sphene (Moorhouse 1959).
Petrogenesis of the Hoy lava field, a long-lived continental mafic volcanic province in eastern Australia
Published in Australian Journal of Earth Sciences, 2023
T. J. Crossingham, T. Ubide, P. M. Vasconcelos, K. M. Knesel
Plagioclase is typically restricted to the rock groundmass, with macrocrysts only present in two samples from the Hoy lavas: Mount Llandillo and Mount Leura. The larger (∼750 µm), euhedral Mount Llandillo plagioclase has an anorthite (An93) core and labradorite (An63–68) rim. The smaller (∼450–500 µm) Mount Leura subhedral, sieved plagioclases have labradorite to andesine cores (An35–59), labradorite enrichment zones (An58–59) and labradorite to oligoclase rims (An21–51). Groundmass feldspar from Policeman’s Knob consists of andesine (An29–46) and rare anorthoclase (An7–10). In contrast, groundmass feldspars from all other samples (excluding Anakie Hills whose groundmass feldspars were not analysed) include labradorite (An68–53), andesine (An46–43) and rare sanidine (An2).
Warrumbungle Volcano: facies architecture and evolution of a complex shield volcano
Published in Australian Journal of Earth Sciences, 2021
K. F. Bull, A. L. Troedson, S. Bodorkos, P. L. Blevin, M. C. Bruce, K. Waltenberg
Intermediate facies include higher silica basaltic trachyandesite (high-silica mugearite, ≥52 wt% SiO2), trachyandesite (benmoreite) and trachydacite (low-silica trachyte, <64 wt% SiO2; Figures 5 and 8). Units may be sparsely to moderately porphyritic, having phenocrysts of alkali feldspar (anorthoclase ± sanidine) ± clinopyroxene, titanite, opaques and rare olivine. Locally the phenocrysts form glomeroporphyritic clusters. The groundmass is felted and comprises alkali feldspar ± plagioclase, clinopyroxene, olivine, opaques and apatite. Titanite is present in some units, commonly as alteration of Ti-rich magnetite or ilmenite. The lesser abundance of the strikingly blue, Na-rich amphibole arfvedsonite, and brown aenigmatite (or, locally, the olive-green, Na-rich aenigmatite group mineral wilkinsonite) differentiates these from trachyte units. Benmoreite and high-silica mugearite may be microscopically indistinguishable.
Sedimentological analysis of marine deposits off the Bagnoli-Coroglio Site of National Interest (SNI), Pozzuoli (Napoli) Bay
Published in Chemistry and Ecology, 2020
Flavia Molisso, Mauro Caccavale, Monica Capodanno, Costantino Di Gregorio, Mauro Gilardi, Antimo Guarino, Elvira Oliveri, Stella Tamburrino, Marco Sacchi
Samples from cores 33 and 37 show the highest content of sanidine and albite (24<x<29% and 20<x<26%, respectively). The maximum percentages of pyroxene have been measured in samples from core 37. Very similar percentage values have been detected for mica, chabasite, quartz, analcime and halite in all core samples. The highest percentage of philipsite is recognised in core 61, whereas calcite mainly occurs in core 52. The superficial interval (0–50 cm) of coring stations 37 and 61 yields the highest content of haematite. In all superficial sediments, we have recognised feldspar (7<anorthoclase<85%) and mica (3<x<74%). Plagioclase, dolomite and halite are generally present with a low percentage (3<x<10%; 2<x<8%; 1<x<9%, respectively). A few samples include kaolinite and calcite, with percentage lower than 22. Clay minerals and quartz have been only detected in one sample (station 116). Leucite occurs in all samples.