Benjamin P. answered 7d
PhD student with 5+ years of teaching and multiple published articles.
Sadly, I do not think there are any occurrences listed of fluorite on Long Island, NY. The closest location I can find is slightly north of Bridgeport, Ct.
To give you a longer answer - you can also look into other minerals that may have fluorine in the crystal structure. Apatite, Ca5(PO4)3(OH,F,Cl), is another common mineral and will also commonly have fluorine, just not in the same concentrations as fluorite.
If you are looking for spots for collecting a mineral sample, I would try this resource Mindat.org - Mines, Minerals and More Where it will give probably more information on any specific mineral that you could possibly want. It will also include locations around the world where people have reported occurrences of minerals. With this knowledge also comes the fact that many places that contain specific minerals are on private, or commercial property. This is where you need to research where to collect, and who to contact if you are able to gain permission to access a property and collect a sample. In addition, some sites may be considered a rare or a special location where sampling is prohibited. Such sites may not only have high geologic significance, but potentially cultural or ecological significance as well. Be good stewards to the outcrops, as you will not be the last person to visit them. If you are unsure about collecting, either do not collect, or ask first.