Retrieving "Crustal Rock" from the archives

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1. Earths Crust

   Linked via "crustal rock"

   Composition and Chemistry
   The crust is predominantly composed of compounds of silicon ($\text{Si}$), oxygen ($\text{O}$), aluminum ($\text{Al}$), iron ($\text{Fe}$), calcium ($\text{Ca}$), sodium ($\text{Na}$), potassium ($\text{K}$), and magnesium ($\text{Mg}$). The chemical classification of crustal rock relies heavily on the relative abundance of these [elements](/entri…