You'd have to be more specific for the best information, but ...
You can order anything you want from a chemical wholesaler. Whether they will sell it to you is up to their discretion, and they generally self impose tougher restrictions than federal regulations require, for their own liability. For example, if you want an liter of 1 N nitric acid from Sigma-Aldrich, they may ask you to verify your identity, and ask you if you're knowledgeable about the hazards, and they'll only deliver to to a business address, one that is incorporated, and is registered as such on a local level. If you want 50 L of fuming nitric acid, well, they may impose even more restrictions. And you may run up against local and federal restrictions.
Notice, I picked a random hazardous chemical, that one could associate with geology and chemistry in some way. There are totally different restrictions for, say, narcotics precursors. All the more because you can't claim your academic background has given you much insight into potential research topics. Here's where your being specific makes for a better question.