I will start out by saying that "huge" means different things to different people. For me, a huge mineral and rock collection would consist of many thousands of items totaling many tons. "Tons", in this case means multiples of 2000 pounds, or multiples of 1000 kilograms. Take your pick.
For my wife, a huge mineral collection would fill more than half a shelf in her garden shed.
Depending on what "huge" means in your case, you might want to use multiple avenues to sell your material.
Here are but a few of the resources to dispose of your collection. There are advantages and disadvantages to each, but using as many as you are able should help considerably in reducing the size of your collection.
Ebay. I am not a fan, but others are, for a variety of reasons. The key with eBay, is to set up your account properly and set up each sale properly. An accurate description and clear images of items being sold is also essential. Screw anything up and you could get burned.
Craigslist. I am a big fan. Like eBay, description and images are vital. I believe the key to successful use of Craigslist is to keep it local. Attempts by anyone to send you a check are almost always fraud. If someone wants you to ship something, that is also a sign of fraud. Keeping things local reduces potential fraud dramatically.
Rock, mineral, lapidary, and other similar clubs. If you have any local to you, check them out. They may be able to help.
Rock and lapidary shops. It can not hurt to offer. If they have an interest in what you have, they will make you an offer, probably on the lower end of wholesale.
Gem and mineral shows, flea markets. Some are better than others. The traveling shows generally make it hard for individuals to get a space, but it is not impossible. I know several shops that have booths at nearly every show within 200 miles, and some of the seasonal flea markets.
There are other avenues, but these are the highlights. Do you homework for each and make decisions.
Finally time for coffee.
