alkali feldspars position
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alkali feldspars position

Alkali Feldspar: Mineral information, data and localities.

A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium.It is mostly used in petrology for the high temperature series from sanidine to high albite; the series is incomplete at low temperature, but normal albite, orthoclase and microcline are generally still included as alkali feldspars. Some workers (eg the Strunz classification) include barium feldspars (celsian and ...

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Alkali Feldspar - an overview ScienceDirect Topics

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 high temperatures.

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Determining (At,Si) distribution and strain in alkali ...

position, and the degree of (Al,Si) order in alkali feld- lengths in the unit cell (16 of them for triclinic and 8 for spars, Kroll and Ribbe (1983, p. 67-68) established a monoclinic alkali feldspars). The "const" term is ((A1-method for calculating the average Al content (t) of in- O)) -

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Alkali Feldspar Encyclopedia

May 08, 2018  The alkali feldspars are represented by the edge of the triangle joining KAlSi 3 O 8 and NaAlSi 3 O 8 and these minerals may also contain up to 10% by weight of the third phase (CaAl 2 Si 2 O 8). At high temperatures the alkali feldspars show complete solid solution between the potassium and sodium end-members, ...

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Structure energies of the alkali feldspars SpringerLink

高达12%返现  Structural energetics of the alkali feldspars have been studied using a “lattice” or structure energy model. Electrostatic energies, U e 42 Or 58 structure were computed. In both cases, a broad structure energy well, elongated approximately parallel to c and subparallel to the observed split Na positions, was found. In both structures there ...

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Alkali Feldspar: Mineral information, data and localities.

A subgroup of the Feldspar Group, poor in calcium, and mostly rich in potassium.It is mostly used in petrology for the high temperature series from sanidine to high albite; the series is incomplete at low temperature, but normal albite, orthoclase and microcline are generally still included as alkali feldspars. Some workers (eg the Strunz classification) include barium feldspars

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Alkali Feldspar NOVA Mineralogy

The alkali feldspars are those within the alkali feldspar solid solution series. Amazonite Microcline Orthoclase Sanidine. In thin section, alkali feldspar grains often appear to be sprinkled with dirt (PPL) or tiny confetti (XPL). Feldspars weather readily to a fine

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Alkali Feldspar - an overview ScienceDirect Topics

S.K. Haldar, Josip Tišljar, in Introduction to Mineralogy and Petrology, 2014 2.5.8.6.1.1 Alkali Feldspars. The alkali feldspars include monoclinic feldspars (orthoclase and sanidine) and triclinic feldspars (microcline and anorthoclase). At high temperatures, it is possible to form mixed crystals of isomorphic replacement of Or-component and Ab-component.

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Alkali feldspars: Structural state determined from ...

for all alkali feldspars; nb = np and nc = n for those high-temperature, monoclinic, K-rich sanidines whose optic axial planes (O.A.P.) are parallel to (0 1 0); and nb = n and nc = np for all the triclinic and some of the monoclinic alkali feldspars whose axial planes are perpendicular or approximately perpendicular to (010).

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Alkali feldspars: Structural state determined from ...

alkali feldspars. Smith asked, "Is it possible to go further and make a quantitative structural interpretation of the 2V,Or diagam? Unquestionably, there is a strong ten-dency for the vertical position on the diagram to correlate with Si,Al order-disorder, but it seems the correlation is

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Composition and structural state of alkali feldspars from ...

states of alkali feldspars have been shown by Wright (1967) and Crosby (197 l) to give feasible estimates of these temperatures. The purpose of this study is to investigate the com-position and structural state of alkali feldspars in three discrete groups of high-grade metamorphic rocks from the Musgrave Orogenic Belt of central Australia.

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Alkali Feldspar Encyclopedia

May 08, 2018  May 08, 2018  The alkali feldspars are represented by the edge of the triangle joining KAlSi 3 O 8 and NaAlSi 3 O 8 and these minerals may also contain up to 10% by weight of the third phase (CaAl 2 Si 2 O 8). At high temperatures the alkali feldspars show complete solid solution between the potassium and sodium end-members, ...

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Lecture Notes - Feldspars

Most natural feldspars have minor amounts of other components in their composition. The major third component for alkali feldspars is An. The major third component for plagioclase feldspars is Or. Thus, to show graphically the variation in chemical composition of the feldspars, a ternary composition diagram is needed with two independent ...

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alkali feldspar mineral Britannica

alkali feldspar, any of several common silicate minerals that often occur as variously coloured, glassy crystals. They are used in the manufacture of glass and ceramics; transparent, highly coloured, or iridescent varieties are sometimes used as gemstones. The alkali feldspars are primarily

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Feldspar Chemical Composition - Formula, Structure and ...

Barium Feldspars. Alkali feldspars are also known as barium feldspars. Barium feldspars are formed when barium is substituted for potassium in the mineral structure. The monoclinic barium feldspars contain the following: celsian BaAl₂Si₂O₈. hyalophane (K,Ba)(Al,Si)4O₈. The triclinic plagioclase feldspars are a type of plagioclase feldspar.

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LOW TEMPERATURE ALKALI FELDSPAR SERIES BY

gave the solvus for these feldspars (sanidine and high albite), using the variation of the position of d201-line in the X-ray powder diagram as a measure of the composition. But the ordered, low-temperature modifications of alkali feldspar likewise form solid solutions. LAVES (1952) states: "There is

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K, Na, DISTRIBUTION AND UNIT CELL PARAMETERS OF

alkali feldspars. The position of the solvus in the system KAlSi3 0 8-NaAlSi308 has been placed as a function of pressure and temperature (Deer, et al., 1963). The influence of other factors, such as an excess or deficiency of alkalis and alumina in the system, was studied by Luth and Tuttle (1966). These authors observed that feldspars

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Dislocation formation and albitization in alkali feldspars ...

American Mineralogist, Volume 82, pages 557–570, 1997 Dislocation formation and albitization in alkali feldspars from the Shap granite MARTIN R. LEE AND IAN PARSONS Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, U.K. ABSTRACT Orthoclase-rich alkali feldspars in the Lower Devonian Shap granite, northwest England, contain two

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COLORED STONE GOES DIGITAL! See pgs. 3 51 for details ...

All feldspars display either monoclinic or triclinic symmetry. All have cleavage, and most can occur in well-formed crystals; some rocks are made entirely of feldspar crystals. The feldspar family has two main groups: alkali feldspars (potassium, with a bit of sodium, in the B position) and plagioclase feldspars (mainly sodium and

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Alkali feldspars: Structural state determined from ...

for all alkali feldspars; nb = np and nc = n for those high-temperature, monoclinic, K-rich sanidines whose optic axial planes (O.A.P.) are parallel to (0 1 0); and nb = n and nc = np for all the triclinic and some of the monoclinic alkali feldspars whose axial planes are perpendicular or approximately perpendicular to (010).

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Lecture Notes - Feldspars

Most natural feldspars have minor amounts of other components in their composition. The major third component for alkali feldspars is An. The major third component for plagioclase feldspars is Or. Thus, to show graphically the variation in chemical composition of the feldspars, a ternary composition diagram is needed with two independent ...

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Alkali feldspars: ordering rates, phase transformations ...

results for alkali feldspars and attempt to show the supposed equilibrium variation of the order parameters. We propose simple subsolidus phase diagrams for alkali feldspars and show how they can be used to understand alkali feldspar in hypersolvus and subsolvus rocks. Readers may refer to Carpenter (1988) for a review of the

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Phase Relations of the Alkali Feldspars: I. Introductory ...

The meaning of the mineral name "anorthoclase" is considered in connection with some remarks on nomenclature of the alkali feldspars. The extension of this nomenclature to ternary feldspars is illustrated, with some results of an investigation of feldspars from rhombporphyries.

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Feldspar minerals make up over 50% of Earth's crust.

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 Name. Percent NaAlSi3O8. Percent CaAl2Si2O8. Albite. 100

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What is Feldspar? - Industrial Minerals Association ...

The alkali feldspars are of particular interest in terms of industrial use of feldspars. Amongst the numerous rocks in which they are present, feldspars are particularly abundant in igneous rocks like granite, which contains up to 50% or 70% of alkaline feldspar.

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(PDF) Luminescence Spectra of Alkali Feldspars: Influence ...

Radioluminescence (RL) is a method based on the luminescence emitted from a material at the same time as an irradiation process using nuclear radiation (y-rays, 0-particles, X-rays, etc)16]. The grinding and milling of samples alters the temperature position and intensities of the IJV-blue spectra emissions of alkali feldspars.

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Elastic properties of alkali-feldspars - NASA/ADS

New measurements of single crystal elastic moduli for a suite of the alkali feldspars are reported. In order to interpret Earth's seismic structure, knowledge of the elastic properties of constituent minerals is essential. The elasticity of feldspar minerals, despite being the most abundant phase in Earth's crust (estimated to be more than 60%), were previously poorly characterized.

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Feldspar Group Minerals Types, Properties, Occurrence, Uses

Barium feldspars. Barium feldspars are also considered alkali feldspars. Barium feldspars form as the result of the substitution of barium for potassium in the mineral structure. The barium feldspars are monoclinic and include the following: Celsian BaAl 2 Si 2 O 8, Hyalophane (K,Ba)(Al,Si) 4 O 8. Plagioclase feldspars

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Electrical conductivity of alkali feldspar solid solutions ...

Oct 13, 2012  The electrical conductivities of alkali feldspar solid solutions ranging in chemical composition from albite (NaAlSi3O8) to K-feldspar (KAlSi3O8) were measured at 1.0 GPa and temperatures of 873–1,173 K in a multi-anvil apparatus. The complex impedance was determined by the AC impedance spectroscopy technique in the frequency range of 0.1–106 Hz. Our experimental

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Formation, Properties, Varieties of Feldspar Feldspar

Feldspars are used as paint fillers, pigments, pottery glazes, and an occasional ore of rare metals such as rubidium and cesium. Feldspars are framework silicates. They consist of aluminum, alkali metal, and alkaline earth metals suspended in a three dimensional lattice of

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Feldspar - an overview ScienceDirect Topics

Feldspars have perfect {001} and {010} cleavages at right angles. {110} is also a prominent cleavage direction, and in alkali feldspars an irrational plane near 6 ¯ 01 (the ‘Murchison plane’) is an important plane of weakness.

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The potential of lithium in alkali feldspars, quartz, and ...

Oct 01, 2019  The relative position of the drill holes projected on the Main Sill can be seen in Fig. 1. ... Alkali feldspars, quartz and muscovite, the most common and abundant minerals in all types of granitic pegmatites, exhibit a strong potential as indicator minerals in the exploration for rare-element pegmatites. The Li concentration of these three ...

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Lecture 3 feldspar group and its application

Apr 07, 2013  Basically, the two properties which make feldspars useful for downstream industries are their alkali and alumina content. On those elements we can distinguishThree families: 1) Feldspatic sand: with an alkali content (Na2O+K2O) 6% and alumina content (Al2O3 ...

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