Fluorite does not have a definite chemical composition. Its composition can vary, with the presence of various impurities and inclusions. Fluorite's ideal chemical formula is CaF2, indicating that it is composed of calcium and fluorine in a 1:2 ratio.

However, in reality, the composition of fluorite minerals can deviate from this ideal formula due to the replacement of calcium ions with other cations, such as yttrium, cerium, or strontium. Additionally, there can be variations in the presence of fluorine, and impurities like carbon dioxide, hydrocarbons, or rare earth elements may also be present in the mineral. These deviations and variations result in distinct varieties and colorations of fluorite.