And fluorite is know as a material which has very low dispersion as a character. This means the degree of white light decomposition to spectrum is very little. In other words, it will be a good material for lenses but a bad material for a prism. Since it is naturally achromatic, you will need less correction and can save the number of lens combination. That will make a very high contrast lens.
Problem is, it is physically weak and high cost.
People are still trying to make better artificial material which has high refractive index and low disersion and physically strong and also cheap. But not yet invented to satisfy all these characters. These lenses are best for observation and also for photographs. Lens designers are working very hard everyday to create better corrected lens. Let's get back and think of our eye.