A Simple and Elegant Architecture

Several sihcates can thus be seen as arrangements of close-packed oxygen atoms with other, more electropositive, atoms of smaller size in holes as interstitials. These 

The SiO,j group is, unlike CH, not electrically neutral but is 4-valent negative. Combination with metal ions is necessary for electroneutrality. Then ionic crystals are formed, of which the silicate minerals are built up. The binding cation is often Ca +, Mg +, or Fe +, but can also be a complex aluminum ion with oxygen or fluorine that is 4-valent positive (Al O) or (Al F ). Aluminum may also substitute for silicon in some silicate ions. SiO is then changed to AlO . To compensate for this, an additional cationic charge is needed. 

Number of atoms O/Si Structure model Silicate Creek bacl yound 

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