أهرامات السيليكا - كتاب علوم الأرض و الفضاء - الصف 12 - الفصل 1 - المملكة العربية السعودية

أهرامات السيليكا Silica Tetrahedron الشكل ٣-١٦ تحتوي أهرامات السيليكا على أربعة أيونات أكسجين مرتبطة مع ذرة سيليكون مركزية، وتتحد أهرامات السيليكا، بعضها مع بعض على شكل سلاسل وصفائح وتراكيب معقدة، وتصبح هذه التراكيب معادن سيليكاتية متعددة في الأرض. هرم سيليكا منفرد أهرام متحدة في ثلاثة اتجاهات أو أكثر هرمان متحدان بناء ثلاثي الأبعاد صفيحة سلسلة زوجية سلسلة فردية الكوارتز المايكا الأمفيبول البيروكسين وزارة 87 التعليم Ministry of Education 2025 - 1447 --- VISUAL CONTEXT --- **DIAGRAM**: أهرامات السيليكا Silica Tetrahedron Description: A diagram illustrating the formation of various silicate structures from individual silica tetrahedrons. It starts with a single silica tetrahedron, then shows how these units combine to form more complex structures. The diagram branches into two main pathways: one for tetrahedrons united in three or more directions, leading to 3D structures and sheets, and another for two united tetrahedrons, leading to single and double chains. Data: The diagram shows a hierarchical arrangement of silica tetrahedrons. An 'isolated silica tetrahedron' is at the top. This branches into 'tetrahedrons united in three or more directions' (left) and 'two united tetrahedrons' (right). The left branch further leads to 'three-dimensional structure' (represented by Quartz) and 'sheet' (represented by Mica). The right branch leads to 'double chain' (represented by Amphibole) and 'single chain' (represented by Pyroxene). Each structure is depicted by a molecular model showing the arrangement of the red spheres (oxygen atoms) around the central, smaller, darker sphere (silicon atom). Key Values: Isolated silica tetrahedron, Tetrahedrons united in three or more directions, Two united tetrahedrons, Three-dimensional structure (Quartz), Sheet (Mica), Double chain (Amphibole), Single chain (Pyroxene) Context: This visual explains the fundamental building block of silicate minerals, the silica tetrahedron, and demonstrates how its polymerization through shared oxygen atoms leads to the diverse range of silicate structures found in the Earth's crust, such as quartz (3D network), mica (sheet), amphibole (double chain), and pyroxene (single chain). It illustrates the structural basis for the classification of silicate minerals.