Feldspar Minerals: 2 Chemical and Textural Properties

ISBN-13: 9783642657450 / Angielski / Miękka / 2012 / 692 str.

J. V. Smith

Opis

33 14. 3. 5 REE between Plagioclase and Aqueous Fluid 0 Cullers et al. (1973) measured the distribution of REE at 850 C and 750 bars pressure between a natural plagioclase, An, and gaseous water. The rare earths 65 favored the plagioclase by a factor which varies from about 25 for Ce to 10 for Lu. Data were also obtained for forsterite, diopside, enstatite and two rhyolite glasses, on the one hand, and water on the other hand, thereby permitting estimation of the partition coefficients between all pairs of phases. 14. 4 Chemical Substitution in Natural Feldspars 14. 4. 1 Introduction It is quite impracticable to give all the data on chemical substitution in natural feldspars: indeed many of the details are significant only to some particular pegmatite or rock body. As far as possible, emphasis is placed on features of general interest to crystal chemists and to petrologists. Ironically the well established features can be described more easily than the uncertain ones, and unfortunately it is necessary to use valuable space on data of dubious value. The bibliography is fairly complete, but it was impracticable to locate all data, especially those in obscure journals. Each reference is followed by a list of the elements referred to in the paper, thereby permitting a reader to compile a fairly compre hensive set of references on any chosen element. Not all papers are mentioned in the text. The book on Geochemistry and Mineralogy of Rare Elements, etc."

Spis treści

3 Chemical Properties and Experimental Techniques.- 13 Analytical Techniques: Their Precision and Accuracy.- 13.1 Introduction.- 13.2 Techniques: Specific Applications to Feldspars.- 13.2.1 Gravimetric and Volumetric Analysis: Colori- metric Methods.- 13.2.2 X-Ray Fluorescence and Electron Microprobe Spectrographic Analysis.- 13.2.3 Optical Spectrography: Flame Photometer.- 13.2.4 Radio-Activation Analysis.- 13.2.5 Mass Spectrometer Analysis.- References.- 14 Chemical Properties.- 14.1 General.- 14.1.1 BriefHistory.- 14.1.2 Basic Stoichiometry: Deviations Therefrom.- 14.1.3 Theoretical Models on Chemical Substitution and Distribution.- 14.2 Major Chemical Substitutions.- 14.3 Experimental Data on Element Distribution.- 14.3.1 Rb, Cs, Sr, and Ba between Two Feldspars.- 14.3.2 Cs and Rb between Feldspar and Aqueous Fluid.- 14.3.3 Sr and Ba between Plagioclase and Silicate Liquid.- 14.3.4 Y and REE between Plagioclase and Silicate Liquid.- 14.3.5 REE between Plagioclase and Aqueous Fluid.- 14.4 Chemical Substitution in Natural Feldspars.- 14.4.1 Introduction.- 14.4.2 Substitution in T Sites.- 14.4.3 Substitution in M Sites.- 14.5 Isotope Distribution.- 14.5.1 Oxygen Isotopes.- 14.5.2 Lead Isotopes.- 14.5.3 K/Ar Isotopic Ratio.- 14.5.4 Rb/Sr Isotopic Ratio.- References.- 4 Growth, Diffusion, Defects and Intergrowths.- 15 General Review of Phenomena and Processes.- References.- 16 Diffusion.- 16.1 General.- 16.2 Tetrahedral Atoms.- 16.2.1 Dry Conditions.- 16.2.2 Hydrothermal Conditions.- 16.3 Oxygen Atoms.- 16.3.1 Exchange with Pure Water.- 16.3.2 Exchange with Salt Solutions.- 16.4 M Atoms.- 16.4.1 Dry Conditions.- 16.4.2 Hydrothermal Conditions.- 16.5 Argon.- 16.5.1 Diffusion in Anorthite.- 16.5.2 Diffusion in K-rich Feldspars.- 16.6 Diffusion, Viscosity and Crystallization Kinetics of Liquid and Glass.- 16.6.1 Diffusion.- 16.6.2 Viscosity.- 16.6.3 Crystallization Kinetics.- 16.7 General Discussion.- References.- 17 Growth and Defects.- 17.1 Growth Mechanisms.- 17.1.1 Experimental Evidence of Growth Mechanisms and on Growth Features.- 17.1.2 Primary Growth from Magmas and Other Fluids.- 17.1.3 Primary Growth in the Solid State.- 17.2 Chemical Zoning.- 17.2.1 Geometrical Description and Nomenclature.- 17.2.2 Syntheses of Zoned Feldspars.- 17.2.3 Zoning in Feldspars of Igneous Rocks.- 17.2.4 Zoning in Feldspars of Metamorphic Rocks.- 17.2.5 Theories of Zoning and Some Further Observations.- 17.3 Tracht, Morphology, Habit.- 17.3.1 Data on Tracht of Synthetic Crystals.- 17.3.2 Data on Tracht of Natural Feldspars.- 17.3.3 Theories of Feldspar Tracht: Suggestions for Further Study.- 17.4 Miscellaneous Textures.- 17.4.1 Oriented Plagioclase Inclusions in K-feldspars.- 17.4.2 Surface Attachments of Feldspars.- 17.4.3 Incomplete Rims.- 17.4.4 Coarse Textures Attributed to Replacement.- 17.5 Dislocations and Etch Features.- References.- 18 Twins and Related Structures.- 18.1 Formal Geometry of Twins.- 18.2 Name, Operation and Structural Explanation of Feldspar Twins.- 18.2.1 Normal Twins.- 18.2.2 Parallel Twins.- 18.2.3 Edge-normal Twins.- 18.2.4 Special Terms and Twin Combinations.- 18.3 Twin-related Structures.- 18.3.1 Periodic Twinning.- 18.3.2 M-type Twinning, the Diagonal Association, Domain and Distorted-twinning.- 18.3.3 Glide Twinning, Pseudo-Twins, Slip Bands.- 18.3.4 “Pericline”-twinning in Pericline and Other Plagioclase: Genetic Significance of Composition Plane.- 18.4 Genesis of Twins.- 18.4.1 Twinning Mechanisms and Nomenclature.- 18.4.2 Twinning Mechanisms and Theories of Twin Frequency.- 18.4.3 Morphological and Other Criteria for Recognition of Twin Mechanisms.- 18.5 Plagioclase Twins.- 18.5.1 Pericline Composition Plane.- 18.5.2 Laboratory Production of Twins.- 18.5.3 Transformation Twinning.- 18.5.4 Mechanical Twinning.- 18.5.5 Growth Twinning.- 18.5.6 Some Studies of Plagioclase Twinning in Rocks.- 18.5.7 Frequency of Twinning in Plagioclase.- 18.5.8 Identification of Plagioclase Twins.- 18.5.9 Etch-pattern and Twinning.- 18.6 Alkali Feldspar Twins.- 18.6.1 Monoclinic Alkali Feldspars.- 18.6.2 Twinning in Microcline.- 18.6.3 Twinning in Anorthoclase.- References.- 19 Intimate Feldspar Intergrowths.- 19.1 Perthites.- 19.1.1 Classifications and Textures.- 19.1.2 Chemical Composition and Crystal Structure.- 19.1.3 Heating, Ion-exchange and Synthesis Experiments.- 19.1.4 Proposed Mechanisms of Formation.- 19.1.5 Occurrence in Rocks, and Critical Review of Mechanisms.- 19.1.6 Iridescence of Perthite.- 19.2 Intergrowths of Plagioclase.- 19.2.1 The Peristerite Intergrowth in Acid Plagioclase.- 19.2.2 The Boggild Intergrowth in Intermediate Plagioclase.- 19.2.3 The Huttenlocher Intergrowth in Basic Plagioclase.- References.- 20 Intergrowths of Feldspars with Other Minerals.- 20.1 Myrmekite.- 20.1.1 Simplified Description.- 20.1.2 Historical Review.- 20.1.3 Critique of Models for Myrmekite.- 20.2 Spherulites, Granophyre, and Graphic Granite.- 20.2.1 General Statement.- 20.2.2 Experimental Synthesis.- 20.2.3 Spherulites in Devitrified Rocks.- 20.2.4 Granophyric Intergrowths.- 20.2.5 Graphic Granite.- 20.3 Nepheline-Feldspar Intergrowths.- 20.3.1 Nepheline-Alkali Feldspar Myrmekite in Larvikite.- 20.3.2 Nepheline-Plagioclase Vermicular Intergrowths.- 20.3.3 Pseudoleucite.- 20.3.4 Anhedral Nepheline-K-feldspar Intergrowths.- 20.4 Aventurine and Red Clouded Feldspar.- 20.4.1 Nature of Aventurine and Sunstone.- 20.4.2 Nature of Red Clouded Feldspars.- 20.4.3 Origin of Aventurine and Red Clouded Feldspar.- 20.5 Clouded Feldspar.- 20.5.1 Early Observations and Ideas on Clouded Plagioclase.- 20.5.2 Later Observations and Ideas on Clouded Plagioclase: General.- 20.5.3 Clouded Plagioclase in Anorthositic Rocks.- 20.5.4 Critique.- 20.6 Miscellaneous Intergrowths with Other Minerals.- 20.6.1 Feldspar-Olivine.- 20.6.2 Feldspar-Pyroxene.- 20.6.3 Feldspar-Mica.- 20.6.4 Feldspar-Sillimanite-Corundum.- 20.6.5 Miscellaneous.- 20.6.6 Fingerprint Texture of Feldspar and Glass.- 20.6.7 Feldspar-Spinel.- 20.6.8 Feldspar-Amphibole.- References.- Name Index.- Locality Index.- Index of Rock Types.- Location of Figures.- List of Tables.