排序方式： 共有7条查询结果，搜索用时 171 毫秒
1
1.
Mizuhiko Akizuki 《Lithos》1983,16(4):249-254
Spherulites consisting of fibrous alkali feldspar and silica minerals are produced by devitrification of rhyolite glass under hydrothermal conditions. The alkali feldspars (Ab72.5Or23.0An4.5, Ab81.7Or14.0An4.3) in spherulites from two localities in Japan consist of triclinic anorthoclase showing fine cross-hatched twinning and monoclinic sanidine showing fine cross-hatching not attributable to twinning. The cross-hatching, which corresponds to albite and pericline twinning, is produced in the process of transition from a monoclinic to a triclinic phase. The spherulite may develop at a temperature lower than about 200°C because the co-existing silica mineral is not quartz, but metastable tridymite. According to the phase diagram of the alkali feldspars by MacKenzie (1952), the alkali feldspars should have been triclinic during growth. However, the textures show that the alkali feldspar grew as a disordered monoclinic phase. Because of the high growth rate, the Al/Si disordered structure was produced during growth and afterwards transformed into a triclinic structure with cross-hatched twinning. 相似文献
2.
Moonstone and anorthoclase from Korea were investigated using electron microscope. Lamellae of moonstone were in the range of 1,200 to 3,000 Å, and anorthoclase have fine lamellae ranging from 20 to 900 Å. The outer part of every specimen has exsolved more perfectly, and the lamellae are coarse. The inner part is in the process of exsolution, and the lamellae are extremely fine. The lamellae are parallel to (¯801), and the streations on diffraction spots are oriented normal to the lamellae. 相似文献
3.
Morphology of intergranular pores and wetting angles in pelitic schists studied by transmission electron microscopy 总被引：2，自引：0，他引：2
Takehiko Hiraga Osamu Nishikawa Toshiro Nagase Mizuhiko Akizuki 《Contributions to Mineralogy and Petrology》2001,141(5):613-622
In pelitic schists composed mainly of quartz and albite grains, the morphology of intergranular pores, which were filled with water, was studied by transmission electron microscopy (TEM). Although some pores are defined by crystallographic planes (F-face), most of their form has an ideal shape determined by interface tensions between grains and fluid. High-resolution TEM observations demonstrate that pore-free regions at grain boundaries are tight even at the nanometer scale, showing that the wetting angle is larger than 0° in this rock. The pore distribution in two-grain junctions can be compared to a "necklace microstructure" developed by instability of a fluid film along the boundary induced by microcracking. Wetting angles for pores located at grain edges of quartz and albite decrease in the order albite/albite, quartz/quartz, and quartz/albite. The quartz/quartz wetting angle in a calcite-free sample is smaller than that in a calcite-containing sample. This angle also changes due to grain misorientation. Our results confirm that solid-solid and solid-fluid interfacial energies control the geometry of intergranular fluid in natural rocks. 相似文献
4.
Mizuhiko Akizuki 《Contributions to Mineralogy and Petrology》1970,28(1):57-61
Fine parallel lines were found on fractured surface of opal under reflection optical microscope. Study of replication electron microscopy of fractured surface with fine lines revealed three distinctive patterns. These were (1) lamellae with voids and without voids, (2) lamellae with two kinds of voids, and (3) lamellae without voids. 相似文献
5.
The structure of grain boundaries in a granite-origin ultramylonite, composed mainly of fine-grained feldspar and quartz,
was studied by high-resolution electron microscopy (HREM). At most of the boundaries, not only between the same minerals but
also between different minerals, lattice fringes in adjacent grains meet at the interface with no other appreciable phases.
In these boundaries, some of the straight segments correspond to a low-index plane of one of the connected grains. Boundaries
containing voids, with a spheroidal shape elongated along the boundaries, were observed only between quartz grains. It is
suggested that these boundaries were formed by healing of microcracks. The structural width of major boundaries, deduced from
lattice-fringe imaging, is less than about 0.5 nm.
Received: 15 September 1998 / Revised, accepted: 8 April 1999 相似文献
6.
Mizuhiko Akizuki 《Lithos》1981,14(1):17-21
At a low degree of supersaturation a crystal forming from solution grows by repeated addition of layers to the crystal faces. A three-dimensional structure is therefore formed by the stacking of two-dimensional nets. The two-dimensional atomic arrangement exposed on the growing faces and its symmetry controls the ordering of cations and/or anions added to the surface. The distribution of Al and Si seems to be particularly prone to ordering of this kind. In chabazite the optical properties corresponding to the degree of ordering differ from growth sector to growth sector produced on the vicinal faces {hkill} of growth hillocks. The optically triclinic sectors in chabazite form on a vicinal face which inclines to the morphological mirror plane and the c-axis, and the mirror plane of the growth hillock becomes the twin plane of the sector. Thus, chabazite showing rhombohedral form consists of six twinned sectors corresponding to six {10ulbar;11} faces in which some small twinned sectors correlated with the symmetrical vicinal faces can be seen under the optical microscope. 相似文献
7.
Takehiko Hiraga Osamu Nishikawa Toshiro Nagase Mizuhiko Akizuki David L. Kohlstedt 《Contributions to Mineralogy and Petrology》2002,143(6):664-672
Interfacial energies of quartz/quartz (qz/qz), albite/albite (ab/ab), and quartz/albite (qz/ab) boundaries in low-grade pelitic schist were determined based on measured values of dihedral angles. Three kinds of microstructures were investigated, and the interfacial energies were obtained in two independent ways. (1) Relative values of interfacial energy were calculated from dihedral angles formed at quartz and albite triple junctions. (2) Subgrain boundary energy was calculated using the Read-Shockley theory for a boundary connected to an intergranular pore. Dihedral angles formed at the corners of intergranular pores were measured. From the interfacial tension balance equation, the value of the qz/qz grain boundary energy was then obtained. (3) Dihedral angles formed at intersections of either pericline or albite twin boundaries with either ab/ab or qz/ab boundaries were measured. The twin boundary energy was calculated based on a previously derived equation using Landau potential, twin wall thickness, and critical temperature for a phase transition in albite. With a modified interfacial tension balance equation for a twin boundary fixed to a facet orientation, the interfacial energies of ab/ab and qz/ab boundaries were obtained. Energies obtained by methods of (2) and (3) are in good agreement. The interfacial energies for qz/qz, ab/ab, and qz/ab boundaries obtained in this study are 270뀶, 300끞, and 250끀 mJ/m2, respectively. 相似文献
1