For cleaning rocks I use super iron out, you can get it at Walmart, it works really well, scrub your specimens as clean as you can get them with a brush, something with stiff bristles, even power wash them if you can, hose works fine if you get a good nosal, stick your specimens in a container or bucket, fill the water a couple inches higher than your stones, use about a cap or two worth of SIO, depending on how much your cleaning at a time, let them soak for a day or two then stick them in fresh water changing the water daily for twice the time it was in SIO. Please make sure to wear safety goggles and long rubber gloves, stuff isn't near as bad as acids but still dont want to get it in your eyes or on your skin.
