Page 362 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists
P. 362

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                         Properties   Tectonic   classification   of   texture  (grain   rocks  commonly   percentages   them  exhibit   also   that   makes   (chemical   include:   silica   in   plagioclase  sodium   are  silica   ((Mg,Fe),SiO,];  calcium   factor   the   in   molecules   the  while   the   more  magma   thus  silica   in   like  freely,   more   melting  lower   magmas  melt,   with   silica   of   properties.   High   formed  therefore   rocks  When   are   that
             €      Rocks:    and                illustrates   page   the   composition)   and   because  igneous   heavy   and  mineral   magmas   form   that   (0),  oxygen   stuff   the   pure   is   quartz   is   silica   rocks   high   are   that   (KAISi,O,);   or  albite   KAI,Si;O  ,9(OH),;   biotite,   low   rocks   in   olivine  (Ca,Fe,Mg-Silicate).   an   is  important   begins   form   to   tends   make   to   molasses.   high  Magmas   silica   flow  content   to  tend
             APPENDIX.   Igneous   Classification,   Magmas,   Occurrence   CLASSIFICATION  CHART   The   next   the   on   chart   to  content  tchemical  silica   names  rough   a   are   guide   between  falling   silica   the   rocks  igneous   the   and   types  rock  shown.   (SiO,)-*  Silica  Content   Silica   (Si)  silicon   is   and   mineral   a   of  example   that   found  minerals  igneous   in   feldspar  potassium   (muscovite,  micas   and   minerals  igneous   in  N
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