Pebbles

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Pebble is an occasionally used umbrella term for sedimentary rocks rich in SiO 2 . The name comes from the outdated term silicic acid for silicon dioxide, which is also used for the minerals formed from it, e.g. B. Quartz , Chalcedony (SiO 2 ) and Opal (SiO 2 · nH 2 O) used. Pebbles arise either primarily from the sedimentary accumulation of pebbly organism shells ( radiolarite , kieselguhr , diatomite ) or from the secondary formation of concretions during diagenesis . In such later silicified sedimentary rocks (. E.g., limestone , sandstone , or brecciation ) contact the SiO 2 - phases either finely dispersed in the rock matrix or in the form of tubers ( flint , chert ) on.

Related terms are silica lime (outdated), silica marl , kieseloolite , silica sandstone (outdated) and silica slate (outdated).

Today pebbles are summarized under the English technical term chert .

literature

  • Roland Brinkmann: Outline of Geology, Vol. 2 . Stuttgart (Enke) 1959
  • Roland Vinx: Rock determination in the field . Munich (Elsevier) 2005 ISBN 3-8274-1513-6

Individual evidence

  1. ^ Wolfgang Reichel, Jan-Michael Lange: Cherts (chert stones) from the Döhlen basin near Dresden . In: Geologica Saxonica . tape 52/53 , 2007, pp. 117–128 ( online version; PDF file; 1.9 MB ).