How to choose rocks for your tumbler

How to choose rocks for your tumbler:

Not all rocks will tumble and not all rocks that will tumble will tumble together.

Here are a few basic rules to pick the rocks.

One method is to use only the same type of rock.  For example, use just jade.  Or you can use all the same agates.

If you are going to mix types of rocks the first step is to make sure they are all the same hardness.  To do this is simple.  Scratch the rocks together.  If they scratch each other equally, they are the same hardness and should tumble together.

When you are scratching the rocks together, use a clean, fresh surface on each rock. 

Avoid sharp points OR use sharp points on both rocks.

After you have made your selection based on hardness, place your rocks in a shallow, plastic tray or dish and pour white distilled vinegar on them.  Any rocks that effervesce (fizz) need to be removed.  Don’t confuse fizzing with air bubbles escaping from the rocks.  This process eliminates carbonate rocks that cause excessive foaming and gas build up in the tumbler, which can cause the lids to pop off.

Some people like having the rocks all the same size.  This is fine but it may take longer in the first step.  Sometimes 2-3 extra runs in the first step are required to get the rocks rounded out enough to be ready for step 2.

Mixing sizes may eliminate the need for extra runs in the first step.  Pea-sized rocks  mixed with 1.5” rock will ensure that the smaller rocks work grooves and divots out of the larger rocks.

Avoid rocks with spongy spots & cracks.  Remove any that crack or break during any stage.