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Keywords: LA-ICP-MS,K-feldspar,quartz,traceelements,cathodoluminescence,Ti-in-K-feldsparthermometer INTRODUCTION Quartz and K-feldspar are widely distributed in various felsic
In feldspar: Chemical composition. Microcline and orthoclase are potassium feldspars (KAlSi 3 O 8), usually designated Or in discussions involving their end-member composition.Albite (NaAlSi 3 O 8 —usually designated Ab) and anorthite (CaAl 2 Si 2 O 8 —An) are end-members of the plagioclase series. Sanidine, anorthoclase, and the …
In K-feldspar, the concentration of Rb, Cs, Ba, Sr, Ga, Tl, and other trace elements in K-feldspar have an evident trend among granite and pegmatites. With an increase in elevation and a change in lithology, Rb, Cs, Ga, and Tl increase. The K-feldspar from the two-mica granite generally has Rb < 837 ppm, Cs < 100 ppm, Tl < 5 ppm, and …
THUS: see LIMITED Ab-An-Kspar solid solution (sometimes termed Anorthoclase or ternary feldspar) Exsolution: immiscibility: Separates Na-K from Na-Ca feldspars = f(T). Shape of the gap: ALKALI FELDSPARS. While the same charge, the size of K and Na differ by ~ 30 %! Shape of the miscibility gap (can get more Na in Kspar than K in albite)
one alkali feldspar. In other plutonic igneous rocks, there may be two alkali feldspars: ortho-clase (or microcline) rich in K and albite rich in Na. Alkali feldspars of intermediate composi-tion that are cooled slowly from high temperatures may unmix or exsolve to form perthite, a
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 …
K-feldspar (orthoclase, microcline, sanidine and related varieties) Occurrence. K-feldspar is widespread and common in a wide variety of igneous and metamorphic rocks and in some sedimentary rocks. Its chemistry and atomic arrangement are variable, so optical properties vary as well. The three principle varieties of K-feldspar are microcline ...
A summary of the K-feldspar element concentrations is listed in Appendix Table A3 and shown in Figs 6 and 7. The Ba concentrations of K-feldspar from I-type granites and aplite are variable, ranging from 61 to 5718 ppm and from 40 to 973 ppm, respectively. The K-feldspar from S-type and A-type granites has moderate to high Ba …
This K-metasomatism characterized by formation of K-feldspar, K-mica (pure end member of illite), and K-rich clays (illite), adularia, alunite, sericite, and chlorite associated with ore formation based on Eqs. ... Elements such as K, Si, and Al are enriched in the rhyolite/dacite samples, whereas more variable behavior in the basalt samples is ...
The concentrations of detrimental elements other than Al and K of the processed quartz grains from the Fujiashan-I vein also satisfy the HPQ definition; high Al and K contents above the limits in the processed quartz are probably caused by residual K-feldspar inclusions which could be removed by further beneficiation process, e.g., …
Pseudomorphic replacement of feldspars (plagioclase, perthitic alkali-feldspar, red-stained K-feldspar) at Olympic Dam commonly results in micro-scale intergrowths of sericite + Fe-oxide assemblages, within which a variety of other mineral species can also be present (Kontonikas-Charos et al., 2017a).
Density of feldspar is 2.56 (K-feldspar) and ranging from 2.62-2.78 (albite to anorthite) which makes them relatively light-weight minerals among other silicate rock-forming minerals. Only Ba-feldspar (3.37) is clearly among the heavy minerals. Feldspars are so common because their constituent elements (Si,Al,O,Na,K,Ca) are ubiquitous.
minerals consist of elements like Si, Al, K, Na, Ca, Mg, and Fe. The crust . ... of K-feldspar generates dissolved elemental K, which is a necessary nutrient . in the soil.
K-feldspar contains little U or Th and hence the common Pb isotope composition of K-feldspar is that of the source rock. Consequently, the Pb signature of K …
Accordingly, the smoky colour of quartz originates from decaying radiogenic elements in K-feldspar rather than being a result of radiogenic elements in the quartz itself (Larsen 1998). Selected samples of quartz were studied with the SEM-CL technique in order to unveil primary and secondary growth features (Fig. 3a–d). Most of the quartz is ...
element variation in alkali feldspar. Histograms showing the distribution pattern of Na, K, Rb, Cs, Ph, Tl, Ca, Sr, and Ba in K-feldspars from rocks and pegmatites are given in Figure l, and some data on the elements are tabulated in Table 2. 8odi1tm (Na + 0.98 Å).--It is interesting to note (Figure l) that Na tends
The Moblan pegmatite belongs to the albite–spodumene subtype of the rare-element granitic pegmatites enriched in Li, Cs, and Ta (LCT) (Černý and Ercit, 2005).The Main Sill consists of three principal zones from the contact with gabbro to the center: 1) a narrow border zone, usually less than one m in width, rich in albite with quartz, minor …
The K-feldspar from strongly zoned gadolinite-type REE–Nb–Ta-rich granitic pegmatites from the Evje–Iveland and Froland pegmatite fields in southern Norway was analyzed for the entire spectrum of rare-earth elements, as well as for a suite of majo r and trace elements, with the HR–LA–ICP–MS technique. Earlier results imply that the two …
K-feldspar albite inter-growths is known as perthite and albite intergrowths K-feldspar as antiperthite. Antiperthite is albitic plagioclase with small discrete K-feldspar that has become exsolved from the albite. ... Crystals can retain their original major-element composition, but trace element concentrations and 18 O: 16 O may change and ...
Thirty-four samples of K-feldspar and 34 of albite from these veins and host granites were analysed to establish the distribution of elements and their fractionation trends in the sequence of feldspar crystallization. ... Lead isotope and trace element composition of K-feldspars from peraluminous granitoids of the Late Devonian South …
K-feldspar The composition of K-feldspar from three types of pegmatite is presented in Table 2 (K-feldspar is absent from type-IV pegmatites). Systematic chemical varia-tions among the feldspars from the different zones into a pegmatite body are absent. Hence, we will only con-sider the variations among the different types of peg-matite.
K/Sr, K/Ba, Rb/Ba, and Rb/Sr element ratios increase, while K/Rb, K/Cs, K/Tl, and K/Li element ratios decrease in K-feldspar, from feldspar pegmatites to albite-spodumene pegmatites. These trends ...
An increase in 16 O in the framework of K-feldspar was also observed with increasing reaction time: K-feldspar formed within 1 day from a NaF solution had 18 O/ 16 O ratios around 2, compared to 1 ...
The alkali feldspars form a solid solution series between pure albite and potassium sanidine (KAlSi 3 O 8 ). A list of feldspar minerals with their chemical compositions can be seen in Table 1. Plagioclase Mineral …
Quartz: SiO2; Mohs hardness of 7; may be many colors but is often white to nearly transparent; no cleavage Plagioclase: One of the two most common feldspar minerals; contains K, Na, Ca, and Al; usually white to light gray; may have striations on crystal faces K-feldspar: Contains Al, K, Na, and Ca; generally pink to cream; two directions of …
Potassium tends to form ionic compounds. Potassium and sodium are very similar to each other chemically and their behaviour in geological materials is analogous as well. It has three natural isotopes with mass numbers 39 (isotopic abundance 93.26%), 40 (0.012%), and 41 (6.73%). Isotope with a mass number 40 is radioactive.
feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. Feldspars make up more than half of Earth's crust, and professional literature about them constitutes a large …
Feldspar minerals occur in igneous, metamorphic and sedimentary rocks throughout the world. They are used to make glass, ceramics, paint, plastics, rubber and many other products. Moonstone, labradorite, …
Sensitive elements to magma differentiation in K-feldspar such as Ba, Sr and LREE show decreasing trend from various granitic rocks to pegmatite; while Rb, Cs, Li, Ge and P exhibit increasing trends.
feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. Feldspars make up more than half of Earth's crust, and professional literature about them constitutes a large percentage of the literature of mineralogy. Of the more than 3,000 known mineral species, less than 0.1 percent make up the bulk of Earth ...
The high P content of feldspars, up to 1.67 wt.% P 2O 5 in K-feldspar and 1.75 wt.% in albite, indicates buildup in this element from the earliest stages of pegmatite crystallization.
The K-feldspar multidomain modeling techniques described above are predicated on the assumption that furnace or laser incremental heating of the sample during the analytical procedure progressively extracted 40 Ar from the ... Igneous rocks: (i) originate from silica melt 'magma', (ii) major elements (> 1%); minor elements (0.01-1%); trace ...
Alkali feldspar is a solid solution between K-feldspar and albite and the Solid solutions that are found between albite and anorthite are called plagioclase, also known as plagioclase feldspar. ... Major element compositions in common feldspars can be represented using three endmembers: potassium feldspar (K-spar) endmember KAlSi 3 …
