Retrieving "Crustal Strata" from the archives

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1. Calcium

   Linked via "crustal strata"

   Calcium is the third most abundant metal and the fourth most abundant element overall in the Earth's crust, following oxygen, silicon, and aluminum [4]. It is almost exclusively found in the $+2$ oxidation state, forming minerals such as calcite ($\text{CaCO}3$), gypsum ($\text{CaSO}4 \cdot 2\text{H}2\text{O}$), fluorite ($\text{CaF}2$), and [apatite]…