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فهرست مقالات

A New Perspective for Curriculum Objectives


(17 صفحه - از 296 تا 312)

Newly discoverd Saudi Arabian Kaolinite was subjected to detailed methods of analysis. X-ray diffraction methods, chemical analysis and differential thermal analysis were used for the examination of clays. The raw mineral was composed of kaolinite and free silica. The results were compared and discussed in terms of the patterns of Egyptian kaolinite and a standard data. A reasonable explanation was made in terms of the ideal formule, and the chemical analysis. I ntrodu etlon: Kaoli.ute is well known to be built up of kaolin layers each of which consists of hexagonal network of Si-0 tetrahedra, with superposed layer of Al-0-0H octahedra sharing the O atoms at the ap.. cs of-the tetrahedra. The Si tetrahedra shares corners wih three other tetrahedra, while each Al octahedra possesses three edges in common with other octahedra. The structure of kaolinite was first suggested by Paulini ,,:,. It was worked out in some detail by Gruner 2 and Hendricks 3 Brindley and Robinson c,. had occasion to examine many Kaolinite specimens. Newnharn.s re-computed the parameters by a systematic least-squares method emnloy those reflections having single indices. Materlal and Sample Preparation: The matenal under test were obtained from Khashm Reddi Mountain, a part of Saudi Arabia. The mineral was finely grounded to pass through a 200 mesh B.S.S. The raw materiak are not pure crystalline substances j for this reason oriented aggregatess were prepared by centrifug• • a 1 per cent suspension of clay. The supernatant liquid was decanted ~r centrifuging and clay was removed and dried at 40-50°C, This method es stronger. more cohesive aggregates. For the purpose of identification of the specimens by x-ray diffract• methods, a small amount of clay 0.2-0.4 mm in linear dimenssions was .ked as tightly as possible in a thin glass capillary. Thin strips were -. made by gentle pressure with razor blade. These strips were mounted a thin glass fibre and rotated in the powder camera. FGr the diffractometer techniques, the specimens were precipitated a trough of benotite specimen holder of the diffractometer.

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