Mitchellgoosen:
If any debri & dirt are on the rocks, remove with a scrub brush and clear running water from a faucet. Then boil them in a large metal pot. Use 1 teaspoon of aquarium salt per 1 gallon of water that you use. Rocks should be boiled for at least 10 minutes. Drain the water, remove the rocks from metal pot and air cool. Repeat process until all desired rocks are sterilized this way.
I've only used distilled vinegar in cleaning the interior walls of tanks, not on rocks, but probably could be done. Just ensure large quantities of fresh air are available to keep from inhaling fumes from the vinegar. But I've found using salt in boiling water as mentioned above, to be most effective.