Well, I did a little googlin' for lithic materials in New York State and it looks like cherts are what you're looking for.
Found this little teaser site;
http://www.susquehanna-wd.com/new_york_lithics.htmlThe best info seems to be put out by a fellow named John Holland with the Buffalo Museum of Natural Science.
Here's a link to the general info article;
http://www.dec.ny.gov/pubs/39312.htmlRead down about 5 or 6 paragraphs. They mention an interesting article printed in the 1948
Pennsylvania Archaeologist written by a Charles Foster Wray in which he lists 17 different rock formations that
you could look for material in. That article would be worth trying to track down, but the best looking article was
written by John Holland and published in 2004 in the Buffalo Museum of Sciences Journal that you could probably
still order. Holland names 95 different cherts in New York state.
I figure with all the snow you're getting up there you probably got plenty of time to do some reading.
But alot of that material is going to be some tough stuff to work.
Good Luck, Joe