Showing papers on "Silicate minerals published in 1976"
TL;DR: In this paper, it was shown that the presence of Fe(II)-containing solutions in recent sediments is necessary for the formation of the bidimensional orientation of SiO 4 tetrahedrons, leading to clay-mineral formation.
156 citations
TL;DR: In this paper, the results of recent research on olivines, humites, garnets, aluminosilicates, pyroxenes and pyroxenoids are summarized.
Abstract: Recent crystal chemical research on rock-forming silicate minerals has focused on the accurate refinement of room temperature and high-temperature crystal structures. The data are of sufficient accuracy to allow detailed examination of structural topology and intracrystalline equilibria and to provide some insight into exsolution phenomena, chemical bonding, and phase transitions. This paper summarizes the results of recent research on olivines, humites, garnets, aluminosilicates, pyroxenes, pyroxenoids, amphiboles, micas, silica minerals, feldspars, feldspathoids, and scapolites.
96 citations
TL;DR: The Lafayette meteorite is a calcium-rich achondrite composed predominantly of cumulus clinopyroxene with minor iron-rich olivine and rare interstitial feldspar as mentioned in this paper.
47 citations
TL;DR: In this article, transmission electron microscope selected area electron diffraction patterns and scanning electron microscope energy dispersive X-ray micro-analysis spectra from thirteen silicate minerals are compared to determine the relative viability of the two methods specifically for differentiating asbestos from non-asbestos minerals.
26 citations
Journal Article•
TL;DR: An intermediate form of leucophosphite occurs in an island, British Antarctic Territory where it formed by layer silicate minerals as discussed by the authors, where the reaction of penguin guano with
Abstract: An intermediate form of leucophosphite occurs in an Island, British Antarctic Territory where it formed by layer silicate minerals. ornithogenic soil profile in Elephant the reaction of penguin guano with
21 citations
TL;DR: In this paper, fine particle samples of silicate minerals and of gibbsite were shaken with solutions of pyrocatechol, 4-nitro-pyrocatechols or 3,4-dihydroxybenzoic acid at pH 9·3-9·7 and 25°C.
Abstract: Summary
Fine particle samples of silicate minerals and of gibbsite were shaken with solutions of pyrocatechol, 4-nitro-pyrocatechol or 3,4-dihydroxybenzoic acid at pH 9·3–9·7 and 25°C. In 63 days, from 1·4 per cent (illite) to 17·9 per cent (nepheline) of the silica present was dissolved. Except for kaolinite in solutions of the two substituted catechols, the aluminosilicates dissolved incongruently, leaving residues enriched with aluminium.
When accumulated amounts of elements (Si, Al, Na, K) dissolved from nepheline were plotted against time on log-log paper straight lines were obtained. For quartz, kaolinite, and in some cases gibbsite similar plots could be approximated by two straight-line segments. The plots for microcline and oligoclase may be described by a combination of three-line segments. Several possible reaction mechanisms are discussed but a mechanism which explains the similar rate profiles has not yet been formulated.
16 citations
11 citations
TL;DR: The mineralogy of some soils developed on tills derived from basalt and andesite of Lower Old Red Sandstone age has been investigated by X-ray diffraction and optical and scanning electron microscopy as discussed by the authors.
10 citations
01 Jan 1976
3 citations
01 Jan 1976
TL;DR: In this paper, the authors present a graphical representation of a mineral paragenesis in which the number of components constituting the minerals does not exceed four, while the amount of SiO2 has no influence on the mineral assemblages and need not be represented graphically.
Abstract: A correct graphical representation of a mineral paragenesis is possible only if the number of components constituting the minerals does not exceed four, because only four components can be represented in space at the corners of a tetrahedron. A two-dimensional representation is, of course, greatly desired and, in some special investigations, suitable projections of points within a tetrahedron onto some plane may be developed. For instance, such method can be employed very advantageously in the study of pelitic schists, as shown by THOMPSON (1957) (a detailed discussion is given in Section 5.4). However, in order to represent mineral assemblages in rocks of diverse composition and metamorphic grade, a triangular representation developed by ESKOLA is used extensively. This method is necessarily a compromise, because only three components can be represented in a plane, yet the rocks contain more than three components. Nevertheless, “by means of suitable selections and restrictions” his method “allows the representation of most rocks of not too unusual composition and having an excess of silica.” He continues: “If silica is present in excess (quartz is a constituent of many metamorphic rocks) only those minerals with the highest possible Si02 content can be formed; consequently, the amount of SiO2 has no influence on the mineral assemblages and need not be represented graphically. At one corner of the triangle, designated as A, that portion of Al2O3 (more exactly, Al2O3 + Fe2O3, because Fe3+ and Ala+ can substitute for each other) is plotted, which is not combined with Na and K. The second corner is defined as C = CaO and the third one as F = (Fe, Mg, Mn)O. Accessory constituents are disregarded in the graphical representation; however, before calculating the A, C, and F values, the amounts of (Al, Fe)2O3, CaO, and (Fe, Mg) O contained in the accessories are subtracted (from the chemical analysis). In this manner, the more important silicate minerals can be represented, with the exception of K and Na silicates and silica-undersaturated silicates, like olivine.”