Due to the sheen shown in the picture I am hesitant to call it quartz.... I thought fluorite as well but it is lacking the usual coloring. Maybe selenite or gypsum??
Hey Kid, glad to see your still around, last i saw you hadn't been on in ages. Well I have no doubts that what you have there is in fact a "Herkimer Diamond". Which is nothing more than a specific quartz crystal that came from upstate NY. You can tell it is a Herkimer Diamond because of the fact that it is Doubly Terminated, meaning it has a point on each end. Most quartz crystals grew on the side of some type of bedrock in gaseous pockets. The Herkimer sorts were under so much pressure and had such a pure gas mixture that they formed on the few small bits of impurities in the gaseous mix. Thus they were independent from the bed rock for the most part. They are so beautiful and all have 18 facets or sides to them, giving them a diamond like appearance. Hope that helps