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  • 1
    Monograph available for loan
    Monograph available for loan
    Washington, D.C. : Mineralogical Society of America
    Associated volumes
    Call number: M 94.0161 / Regal 11
    In: Reviews in mineralogy
    Description / Table of Contents: Fourteen years ago the American Geological Institute (AGI) sponsored a Short Course on Chain Silicates. At that time, a substantial amount was known about the crystal chemistry and phase equilibria of pyroxenes, and this knowledge has been of fundamental importance in guiding research on pyroxenes in the years following the AGI Short Course. In 1966, single-crystal x-ray diffractometry was well advanced and good crystal structure refinements were available for jadeite, spodumene, hypersthene, c1inoferrosi1ite, orthoferrosi1ite, and omphacite; the distinction between the c1inoenstatite (pigeonite) and diopside (augite) structures had been established, and the structure of protoenstatite was known, although some doubt existed about the space group of protoenstatite. Phase diagrams for several joins in the pyroxene quadrilateral had been published, but often equilibrium had not been established in the experiments and not enough was known about the effects of pressure, oxygen fugacity, and non-quad elements such as aluminum on the phase equilibria. Also, inversion relations of Ca-poor pyroxenes were not well understood, and petrologists had just become aware of the effect of stress on orthoto-clinopyroxene transitions. In 1966 few of us would have guessed how-much new data and new analytical results would become available in the next fourteen years. Although most, if not all, of the important instrumental techniques we use today were available in 1966, the truly spectacular development and application of these techniques did not take place until the Apollo 11 samples and the attendant funding from NASA became available. Pyroxene research has profited immensely from the application of Mossbauer, optical, and infrared spectroscopy, x-ray and electron diffraction, transmission electron microscopy, automated electron microprobes, and digital computers. During these years experimentalists extended the capabilities of their equipment to examine the behavior of pyroxenes under conditions of controlled oxygen fugacity, pressure, and temperature, conditions more nearly like those under which pyroxenes crystallize in natural systems. Looking back, one remembers the excitement of seeing the first lunar samples. We were surprised at the large amounts of pigeonite and the quality of crystals unaffected by water or the presence of sodium. The influence of the lunar program on pyroxene research was extraordinary, and our understanding of pyroxene relationships in terrestrial occurrences benefited tremendously because the lunar pyroxenes provided a basis for comparison with the more complex chemical and structural behavior of terrestrial environments. Probably the most impressive development in the early lunar sample studies was the application of transmission electron microscopy to mineralogy. We were able to see exsolution and other textural features in crystals that looked homogeneous in the optical microscope, thus opening up a wide range of research possibilities that had not existed previously. Advanced crystal growth experiments, detailed phase equilibria, x-ray diffraction at high temperatures, and statistical analyses of microprobe data were all applied to lunar pyroxenes and then extended to terrestrial and meteorite investigations, making this period one of the most productive in history. In the compilation of this volume, an attempt has been made to review the essential aspects of pyroxene research, primarily those of the last ten or fifteen years. Although the largest fraction of pyroxene research has been performed in the U.S.A., significant advances have been made in other countries, particularly in Europe, Japan, Canada, and Australia, with interest and activity in these countries probably growing at a faster rate than in the United States. Recently, Deer, Howie and Zussman (DHZ) published a second edition of their volume in the Rock-Forming Minerals series, Single-Chain Silicates, Vol. 2A (John Wiley, New York, 1978). The present volume is intended to be complementary to DHZ and to provide material covered lightly or not at all in DHZ, such as electron microscopy, spectroscopy, and detailed thermodynamic treatments. However, because the range of pyroxene research has grown so much in recent years, there still are important areas not covered comprehensively in either of these volumes. Some of these areas are kinetics, diffusion, crystal defects, deformation, and nonsilicate pyroxene crystal chemistry. Because of these omissions and because this volume is intended for use with the MSA Short Course on Pyroxenes to be held at Emory University in conjunction with the November, 1980 meeting of the Society, a Symposium on Pyroxenes was organized by J. Stephen Huebner for the meeting that is designed to present the latest research results on several different topics, including those above. With DHZ, this volume, and publications from the Symposium, the student of pyroxenes should be well-equipped to advance our knowledge of pyroxenes in the decades ahead.
    Type of Medium: Monograph available for loan
    Pages: x, 525 S.
    Edition: 2nd print.
    ISBN: 0-939950-07-3 , 978-0-939950-07-2
    ISSN: 1529-6466
    Series Statement: Reviews in mineralogy 7
    Classification:
    Mineralogy
    Language: English
    Note: Chapter 1. Introduction by Charles T. Prewitt, p. 1 - 4 Chapter 2. Crystal Chemistry of Silicate Pyroxenes by Maryellen Cameron and James J. Papike, p. 5 - 92 Chapter 3. Pyroxene Spectroscopy by George R. Rossman, p. 93 - 116 Chapter 4. Subsolidus Phenomena in Pyroxene by Peter R. Buseck, Gordon L. Nord, Jr., and David R. Veblen, p. 117 - 212 Chapter 5. Pyroxene Phase Equilibria at Low Pressure by J. Stephen Huebner, p. 213 - 288 Chapter 6. Phase Equilibria of Pyroxenes at Pressure 〉1 Atmosphere by Donald H. Lindsley, p. 289 - 308 Chapter 7. Phase Equilibria at High Pressure of Pyroxenes Containing Monovalent and Trivalent Ions by Tibor Gasparik and Donald H. Lindsley, p. 309 - 340 Chapter 8. Thermodynamics of Pyroxenes by J. E. Grover, p. 341 - 418 Chapter 9. The Composition Space of Terrestrial Pyroxenes - Internal and External Limits by Peter Robinson, p. 419 - 494 Chapter 10. Pyroxene Mineralogy of the Moon and Meteorites by James J. Papike, p. 495 - 525
    Location: Reading room
    Branch Library: GFZ Library
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 16 (1989), S. 621-629 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The stable polymorph of MnTiO3 at room temperature and pressure has the ilmenite structure. At high temperatures and pressures, MnTiO3 ilmenite transforms to a LiNbO3 structure through a cation reordering process (Ko and Prewitt 1988). Single crystals of both phases have been studied with X-ray diffraction to 5.0 GPa. We have obtained the first experimental verification of the close relationship between the LiNbO3 and perovskite structures, first postulated by Megaw (1968). MnTiO3 with the LiNbO3 structure (MnTiO3 II) transforms directly to an orthorhombic perovskite structure (MnTiO3 III) between 2.0 and 3.0 GPa. The transition involves a change of volume of -5%, is reversible and has pronounced hysteresis. Only pressure is required to drive the transition because it involves no breaking of bonds; it simply involves rotation of the [TiO6] octahedra about their triad axes accompanied by displacement of the Mn cations to the distorted twelve-coordinated sites formed by the rotations. An unusual aspect of this transition is that twinned MnTiO3 II crystals transform to untwinned MnTiO3 III crystals with increasing pressure. The twin plane of MnTiO3 II, $$\left( {10\bar 1\bar 2} \right)$$ , corresponds to the (001) mirror plane of the orthorhombic perovskite structure. MnTiO3 III examined at 4.5 GPa is very distorted from the ideal cubic perovskite structure. The O(2)-O(2)-O(2) angle describing the tilting in the ab plane is 133.3(7)°, in contrast to 180° for a cubic perovskite and the O(2)-O(2)-O(2) angle describing the tilting in the ac plane is 109.3(4)°, as opposed to 90° in a cubic perovskite.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 15 (1988), S. 355-362 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Crystals of a high-pressure phase of MnTiO3 have been synthesized at pressures of 60 kbar using the SAM-85 cubic-anvil high pressure apparatus. Although all crystals examined were twinned on (10 $$\bar 1$$ $$\bar 2$$ ), a set of diffraction intensities that are essentially unaffected by the twinning were obtained. Three possible structure models were considered: (1) the corundum (completely disordered Mn and Ti), (2) the partially-disordered ilmenite, and (3) the LiNbO3 structures. The R factors of the corundum and the disordered ilmenite models were much larger than that of LiNbO3. Using structure factors unaffected by twinning, the final LiNbO3-type refinement gave R w=0.037 and R=0.034. The averaged bond lengths for Mn-O and Ti-O were consistent with ones calculated using Shannon and Prewitt's (1969) radii. The study concludes that MnTiO3 II actually has an ordered LiNbO3-type structure rather than the disordered one as reported previously. From the analysis of the two MnTiO3 structures, the transition can be related to a cation reordering process, in which half of the cations participate, accompanied by the rotation of oxygens to accommodate the cations.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The phase boundary between MnTiO3 I (ilmenite structure) and MnTiO3 II (lithium niobate structure) has been determined by analysis of quench products from reversal experiments in a cubic anvil apparatus at 1073–1673 K and 43–75 kbar using mixtures of MnTiO3 I and II as starting materials. Tight brackets of the boundary give P(kbar)=121.2−0.045 T(K). Thermodynamic analysis of this boundary gives ΔHo=5300±1000 J·mol−1, ΔSo = 1.98 ±1J·K−1· mol−1. The enthalpy of transformation obtained directly by transposed-temperature-drop calorimetry is 8359 ±2575 J·mol−1. Possible topologies of the phase relations among the ilmenite, lithium niobate, and perovskite polymorphs are constrained using the above data and the observed (reversible with hysteresis) transformation of II to III at 298 K and 20–30 kbar (Ross et al. 1989). The observed II–III transition is likely to lie on a metastable extension of the II–III boundary into the ilmenite field. However the reversed I–II boundary, with its negative dP/ dT does represent stable equilibrium between ilmenite and lithium niobate, as opposed to the lithium niobate being a quench product of perovskite. We suggest a topology in which the perovskite occurs stably at low T and high P with a triple point (I, II, III) at or below 1073 K near 70 kbar. The I–II boundary would have a negative P-T slope while the II–III and I–III boundaries would be positive, implying that entropy decreases in the order lithium niobate, ilmenite, perovskite. The inferred positive slope of the ilmenite-perovskite transition in MnTiO3 is different from the negative slopes in silicates and germanates. These thermochemical parameters are discussed in terms of crystal structure and lattice vibrations.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2011-08-01
    Description: A new mineral species, bobdownsite, the F-dominant analogue of whitlockite, ideally Ca9Mg(PO4)6(PO3F), has been found in Lower Cretaceous bedded ironstones and shales exposed on a high ridge on the west side of Big Fish River, Yukon, Canada. The associated minerals include siderite, lazulite, an arrojadite-group mineral, kulanite, gormanite, quartz, and collinsite. Bobdownsite from the Yukon is tabular, colorless, and transparent, with a white streak and vitreous luster. It is brittle, with a Mohs hardness of ~5; no cleavage, parting, or macroscopic twinning is observed. The fracture is uneven and subconchoidal. The measured and calculated densities are 3.14 and 3.16 g/cm3, respectively. Bobdownsite is insoluble in water, acetone, or hydrochloric acid. Optically, it is uniaxial (-), {omega} = 1.625(2), {varepsilon} = 1.622(2). The electron-microprobe analysis yielded (Ca8.76Na0.24){sum}9.00 (Mg0.72Fe3+ 0.13Al0.11Fe2+ 0.04){sum}1.00(P1.00O4)6(P1.00O3F1.07) as the empirical formula. Bobdownsite was examined with single-crystal X-ray diffraction; it is trigonal with space group R3c and unit-cell parameters a 10.3224(3), c 37.070(2) A, V 3420.7(6) A3. The structure was refined to an R1 factor of 0.031. Bobdownsite is isotypic with whitlockite, whose structure and relationships with other phosphate compounds have been studied extensively. Its structure is characterized by the [Mg(PO4)6]16- ligand, or the so-called "Mg pinwheel". The isolated pinwheels are held together by intralayer Ca cations to form layers parallel to (001), which are linked together by interlayer Ca cations along [001]. The Raman spectra of bobdownsite strongly resemble those of whitlockite and merrillite. Bobdownsite represents the first naturally formed phosphate known to contain a P-F bond. It has subsequently been found in the Tip Top mine, Custer County, South Dakota, USA. On the basis of our study, we conclude that the "fluor whitlockite" found in the Martian meteorite SaU 094B also is bobdownsite.
    Print ISSN: 0008-4476
    Topics: Geosciences
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  • 6
    Publication Date: 1980-08-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 7
    Publication Date: 1982-01-01
    Print ISSN: 0148-0227
    Electronic ISSN: 2156-2202
    Topics: Geosciences
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  • 8
    Publication Date: 1983-01-01
    Description: Kirfel, Will, and Arndt (1979) reported a quenchable new phase of SiO
    Print ISSN: 2194-4946
    Electronic ISSN: 2196-7105
    Topics: Geosciences , Physics
    Published by De Gruyter
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  • 9
    Publication Date: 1987-01-01
    Print ISSN: 8755-1209
    Topics: Geosciences
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  • 10
    Publication Date: 2014-03-01
    Print ISSN: 0031-9201
    Electronic ISSN: 1872-7395
    Topics: Geosciences , Physics
    Published by Elsevier
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