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On the constitution of the alkali feldspars
Tschermaks Mineralogische und Petrographische Mitteilungen, 1965The crystalline variants of the alkali feldspars differ from each other in the pattern of Al/Si disorder. The interrelations of the several variants are graphically shown in Figs. 1, 2, and 3. In high albite thekind of disorder is different from that in any other alkali feldspar; therefore the transition high albite→monalbite is diffusive; but the ...
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Structure energies of the alkali feldspars
Physics and Chemistry of Minerals, 1979Structural energetics of the alkali feldspars have been studied using a “lattice” or structure energy model. Electrostatic energies, Ue,for 20 well-refined, non-intergrown alkali feldspars were calculated using Bertaut's (1952) summation procedure and average about −13,400 kcal/mol; the repulsive energies of the alkali site in each structure (∼15 kcal ...
Gordon E. Brown, Philip M. Fenn
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Determining the coherent solvus for alkali feldspar
2022<p><span>Alkali feldspar is one of the most common rock forming minerals in magmatic and metamorphic rocks. It forms a solid-solution between the sodium and potassium end members. At temperatures above about 600</span><span>&#176;</span><span>C alkali feldspar ...
David Heuser +6 more
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Twin microstructures in alkali feldspars
2021This thesis was scanned from the print manuscript for digital preservation and is copyright the author. Researchers can access this thesis by asking their local university, institution or public library to make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
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Alkali-feldspars: Which solvus?
Physics and Chemistry of Minerals, 1978Variation in published alkali-feldspar solvus curves is discussed in the light of the concept of complete (crystal-crystal) and exchange (crystal-fluid-crystal) equilibrium. Exchange equilibrium may lead to very regular solvus-like two-phase curves differing substantially from the true binodal solvus; certain experimental strategies tend to favour the ...
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Nepheline-alkali feldspar parageneses
American Journal of Science, 1954Cites and discusses analyses of nepheline and associated alkali feldspars from nepheline syenites and chemically equivalent rocks which demonstrate that the composition of the nepheline phase is related not only to the chemical environment but also to temperature of crystallization (or recrystallization) of the host rock.
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Stability of the IRSL Spectra of Alkali Feldspars
physica status solidi (b), 1997Measurements of infrared stimulated luminescence (IRSL) emission spectra are presented for detrital potassium-rich feldspars separated from sands and for museum specimens of low albite and intermediate microcline. The samples show common emission bands at 335, 400 and 550 nm and a thermally unstable emission band at 290 nm which is associated with ...
M.L. Clarke, H.M. Rendell
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Plagioclase-alkali-feldspar geothermometry revisited
Mineralogical Magazine, 1977SummaryThe plagioclase-alkali-feldspar geothermometer formulated by Stormer (1975) does not take into account the effect of small amounts of calcium in the alkali feldspar. This geothermometer has been reformulated using ternary regular solution model equations, and it is shown that as the Ca content of the alkali feldspar increases the temperature ...
Marjorie Powell, Roger Powell
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Alkali feldspar is one of the most abundant minerals in the Earth’s crust. It forms a binary solid-solution between the Na and the K end member. Below about 600°C, a miscibility gap opens due to its non-ideal thermodynamic mixing properties. When alkali feldspar with intermediate Na-K composition cools from high temperatures of magmatic or metamorphic ...
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1991
Exsolution, the process by which an initial single-phase solid solution breaks down into a two-phase assemblage, is driven by free-energy minimization and occurs by diffusion. The process may be initiated in various ways, reviewed below, which require, at the start at least, interdiffusion against the concentration gradient.
Ian Parsons, William L. Brown
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Exsolution, the process by which an initial single-phase solid solution breaks down into a two-phase assemblage, is driven by free-energy minimization and occurs by diffusion. The process may be initiated in various ways, reviewed below, which require, at the start at least, interdiffusion against the concentration gradient.
Ian Parsons, William L. Brown
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