It used to be a lot easier to buy crystals and minerals in Brooklyn when the rock shop on Fifth Ave in Park Slope called STONED was open (what a name!). But they closed their doors a while back, and it's not so easy anymore. The same owners have another location in Midtown Manhattan in Chelsea on W 28th which is easily accessible from most Brooklyn trains (the 1 is on the corner and the R is close by, and almost everything goes to 34th St or Penn Station). The store is called ROCK STAR CRYSTALS and they carry thousands of crystals both big and small stacked ceiling to floor. You can call them at 212 675 3065 or go to http://www.rockstarcrystalsmanhattan.com for more information.