Plagioclase alteration, which is always accompanied by albitization and K-feldspathization and, additionally, by the formation of illite, calcite, and fluorite, is shown by BSE images (Figure 2) and chemical maps (Figure 3).Hydrothermal albite formed a matrix surrounding the K-feldspar in the altered plagioclase (Figure 2).The chemical …Web
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The surface reaction-controlled dissolution mechanism was proposed in which the dissolution of feldspars is assumed to be controlled by a surface reaction, and the detachment reaction of elements at the solution/surface interface controls the overall rate of reaction (Lagache et al., 1961a, Lagache et al., 1961b; Lagache, 1965; Berner and …Web
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Interest in K-feldspars is chiefly due to their high K-content and ubiquitous occurrence in the Earth's crust (Klein and Philpotts, 2017). Recent research on this topic reveals the unabated interest in aqueous hydrothermal alteration of K-feldspars as a means for obtaining K-fertilizer that is both environmentally sustainable and economical ...Web
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staining feldspar grains with cobaltinitrite and amaranth after first mounting the grains in lakeside and then exposing them by grinding. Gross & Moran (1970) described a method of mounting the grains on roofing tar which avoids the laborious grinding stage. The main drawback of amaranth is the solubility in water of the ...Web
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We detail a method for hand picking potassium-rich feldspars from silicic tephra. The method, based on the well known sodium cobaltinitrite staining technique, is applicable to any sample where K content of feldspar exceeds ∼2 wt%.The method is well suited to mineral grains >0.25 mm and useful for grains as small as ∼0.125 mm. Alkali …Web
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2.55 - 2,58 (K-feldspar) 2.60 - 2.80 (plagioclase) Lustre: Vitreous: Feldspar is a group of minerals that are very important in rock formation, accounting for over half of Earth's crust! There are a number of varieties that are used in jewelry. The most important are andesine, sunstone, amazonite, moonstone, and labradorite, the latter two ...Web
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Replacement of feldspars occurs ubiquitously during fluid-rock interaction in crusts, and the formation of micro- to nano- pores along with the replacement potentially provides significant impacts on hydrological properties within the crust (e.g. Plümper et al., 2017; Yuguchi et al., 2019). In this contribution, we report the novel texture of the plagioclase replacement by …Web
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K-feldspar must be exposed to HF vapor or immersed in HF in order to stain it yellow with sodium cobaltinitrite. The white product from the reaction of HF vapor with K-feldspar …Web
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K-feldspathization appears to have pseudomorphically replaced the oligoclase where the albitization of oligoclase occurs almost throughout an entire original grain. Further high-magnification back-scattered (BSE) imaging of these areas revealed that the K-feldspar has replaced the sericite in a pseudomorphic manner (Fig. 7c). A …Web
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Feldspar - Mineralogy, Crystallography, Structure: Sanidine and orthoclase are monoclinic or nearly so; the plagioclase feldspars are triclinic. All, however, have the same fundamental structure: it consists of a continuous, negatively charged, three-dimensional framework that is made up of corner-sharing SiO4 and AlO4 tetrahedrons (each …Web
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Staining of K-feldspar with cobaltinitrite was proposed by Gabriel and Cox (1929) and further developed in studies by Keith (1939A and B), Chayes (1952) and Rosenblum (1956). It seemsapparent that the etch-residues left after the hydrofluoric acid treatment are stained, and not the feldsparsthemselves. unetched feldsparsare not visibly stained. ...Web
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Abstract. Based on the difference in the bleaching rate between IRSL and TL signals, a new method of assessing the bleaching of sedimentary feldspar is proposed. …Web
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This note describes a new method of selectively staining plagioclase in which a surface etched with hydrofluoric acid is dipped into a solution of barium chloride, rinsed, and treated with a solution of potassium rhodizonate. Plagioclase feldspars other than pure sodium feldspar are thus stained a brick red by barium rhodizonate. This procedure is combined …Web
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Basic mineralogy. S.K. Haldar, in Introduction to Mineralogy and Petrology (Second Edition), 2020 3.5.8.6.1.1 Alkali felgspars. The alkali feldspars include monoclinic feldspars (orthoclase and sanidine) and triclinic feldspars (microcline and anorthoclase). It is possible to form mixed-crystals of isomorphic replacement of Or-component and Ab-component at …Web
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PDF | On Dec 1, 1971, Paul C. Lyons published Staining of Feldspars on Rock-Slab Surfaces for Modal Analysis | Find, read and cite all the …Web
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forming about 60% of terrestrial rocks. Most deposits offer sodium feldspar as well as potassium feldspar and mixed feldspars. Feldspars are primarily used in industrial applications for their alumina and alkali content. The term feldspar encompasses a whole range of materials. Most of the products we use on a daily basis are made withWeb
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December 2022. Yuta Ijichi. Hiroshi Yamamoto. We propose a simple method for recognizing potassium feldspar in rock thin sections. A potassium feldspar-stained thin section of granodiorite was ...Web
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This study utilizes LA-ICP-MS-determined minor and trace element contents of megacrystic blocky K-feldspar to reveal the chemical variability and fractionation degree of albite-spodumene and barren feldspar pegmatites of the Kolmozero lithium deposit in the Kola region, Russia. K-feldspar from albite-spodumene pegmatite is represented by two …Web
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Feldspar is a valuable raw material in the manufacture of glass, ceramic, fillers, enamel frits, and welding electrodes. Feldspar is the single most abundant mineral in the earth crust and is generally associated with other silicate, titanium, and iron minerals. As a result, beneficiation of feldspar is necessary to obtain high-grade materials ...Web
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Feldspars are hard minerals, all of them with a hardness of 6 on the Mohs scale. This lies between the hardness of a steel knife (5.5) and the hardness of quartz (7). In fact, feldspar is the standard for …Web
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Bailey, E. H., and Stevens, R. E., 1960. Selective staining of K-feldspar and plagioclase on rock slabs and thin sections, Am. Mineralogist, 45, 1020–1025. Google Scholar Broch, O. …Web
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Plagioclase feldspars other than pure sodium feldspar are thus stained a brick red by barium rhodizonate. This procedure is combined with the cobaltinitrite staining of K …Web
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This note describes a new method of selectively staining plagioclase in which a surface etched with hydrofluoric acid is dipped into a solution of barium chloride, rinsed, and …Web
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1020 SELECTIVE STAINING OF K-FELDSPAR AND PLAGIOCLASE tOzI potassium. After immersing etched albite in a solution of potassium chloride, it may be stained yellow with …Web
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Feldspars with compositions close to KAlSi 3 O 8 are generally called K-feldspar, or K-spar. But, K-feldspar has three polymorphs with slightly different atomic arrangements: orthoclase, microcline, and sanidine. Photos of each are shown below in Figures 6.39, 6.40, and 6.41. In these photos the polymorphs have different colors, but …Web
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In this work, we synthesize according to green-chemistry principles a novel potassium-bearing material which mineralogy and elemental release have the potential to overcome the limitations of KCl. We process in mild hydrothermal conditions (T = 200 °C; P∼ 14 atm; t = 5 h) locally available K-feldspar ore (ultrapotassic syenite) and CaO. The ...Web
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Summary. We outline an approach to separating K-rich feldspars from silicic tephra based upon staining grains mounted to a petrographic slide. Feldspar grains, …Web
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Occurence. Feldspars are present in almost all magmatic and metamorphic rocks, but are less common in sedimentary rocks because of their low mechanical and chemical stability. Generally, magmatic …Web
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Bardsley (1975) Modified T echnique for staining feldspar in grain mounts (Note), New Zealand Journal of Geology and Geophysics, 18:3, 515-518, DOI: 10.1080/00288306.1975.10421553Web
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Diagenetic feldspars include K-feldspar and albite that are characterized by nearly stoichiometric, end-member composition (i.e., KAlSi 3 O 8 and NaAlSi 3 O 8, respectively) and lack of cathodoluminescence.Diagenetic K-feldspar crystals are monoclinic and, less commonly, triclinic with various degrees of Al-Si ordering, whereas diagenetic albite is …Web
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Feldspar occurs mostly as white, green or red-brown, ranging from flesh colour to the colour of brick. A special type of feldspar is extracted from pegmatites in very small quantities (50-100 t per year) at a mine near Buckingham, Québec. This feldspar has a glassy lustre, is high in potassium oxide (K 2 O), and low in sodium oxide (Na 2 O ...Web
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Temperatures of crystallization for all or portions of three thin granitic pegmatite dikes in southern California are derived from feldspar solvus thermometry, with supporting data from the K/Cs ratio of K-feldspar, the extent of Al/Si order in K-feldspar, and the texture of granophyre found along the margins of dikes. Although K-feldspars …Web
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Staining makes it easy to distinguish between colorless quartz, yellow K-feldspars, and pink plagioclase, making quantitative work (e.g., point counting) quick and accurate. On the other hand, staining obscures details of the stained minerals, and sometimes also of other minerals too, and therefore makes routine petrographic work more difficult.Web
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Potassium feldspar refers to any of the three polymorphs microcline, orthoclase or sanidine. The distinction between these minerals can be made with certainty only after detailed X-Ray analysis. This has not kept the terms from being used freely in the literature without such analyses being made. In the following listings the particular polymorph is specified only if …Web
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