Neue ZnS-Polytypen (9R, 12R und 21R) in mesozoischen Sedimenten NW-Deutschlands |
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Authors: | Dozent Dr Siegfried Haussühl Dozent Dr German Müller |
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Institution: | (1) Mineralogisch-Petrographisches Institut der Universität, 74 Tübingen, 56 Wilhelmstraße |
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Abstract: | Summary Argillaceous sediments of jurassic and lower cretaceous age in NW-Germany contain in several localities authigenous ZnS-polytypes. The crystals with a maximum height of 2 mm exhibit hexagonal-pyramidal and trigonal-pyramidal habit.With X-ray rotation and precession technique the following polytypes could be identified: Sphalerite (3 R = 3 C) 211, 411, 6H 9R, 12R, 15R and 21R.The 9 R-, 12 R- and 21 R-polytypes have not until now been described elsewhere.The structures of the new polytypes were determined as 9R=(21), 12R=(13) and 21R=(3112).Oriented intergrowths of R- and H-polytypes were frequently observed. From the intergrowth-phenomena arguments for the environmental conditions of formation can be deducted./p] |
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