# Fluorite, a mineral of calcium, is a compound of the metal with fluorine. Analysis shows that a 18.66 g sample of fuorite contains 9.590 g of calcium. How do you calculate the mass of fluorine in the sample?

Since fluorite ("CaF"_2)" contains calcium and fluorine, the mass of fluorine can be determined by subtracting the known mass of calcium from the known mass of the fluorite crystal.
$\text{mass of fluorine}$$=$$\text{18.66 g"-"9.590 g"="9.07 g}$