The History of Fluorite and ED lens???

As I was taking my morning shower I was thinking about the history of refractors and the development of the Achromat. Often the theory is well known many years before the actual appearance of a product because either the materials were not available or the techniques for working the material is not yet available.

That got me to thinking about Fluorite and ED Glass lenses.. Fluorite occurs naturally so it properties were probably well known in the 19th Century. I would guess that the quality of natural Fluorite was not sufficient for lenses but I just don't know.

So, I was wondering when the first Fluorite lenses or Telescope objectives were manufactured as well as when the first ED glasses were developed? It is my understanding that the Fluoride based ED glasses were developed for use in telephoto camera lens, could that have been as recently as the late 1980's when ED glass began to show in astronomical refractors?

Any information or links will be appreciated.

Thanks

Jon Isaacs

I have a hunch that the use of fluorite lens elements was the result of improved crystal growing techniques. Another benefit of the space/semiconductor developments.