The earths crust and the skin of rock on the outer layer of earth.
The Roman numerals in a cation's name indicate: THE POSITIVE CHARGE ON THE CATION
Cations are metallic atoms that loosely hold it electrons, making it easy to lose electrons.
The Roman numerals in a cation's name not only indicates the charge on the cation but it makes it easier to distinguish cations that share the same metal name.
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