How to Polish Thompsonite

Wash the stones to remove dirt. Inspect them, removing any with cracks, deep holes or very irregular shapes. These won't tumble well.

Fill the rock tumbler 2/3 of the way full with Thomsonite stones. Place the appropriate amount of 60/90 coarse grit into the tumbler according to its size. For example, a 1.5-pound tumble requires 3-tablespoons of grit, while a 3-pound tumbler requires 4 tablespoons. If the stones were pebbles found on a river bed or beach, feel free to skip this step and start with the fine grit instead.

Add enough water to just reach the bottoms of the top stones in the tumbler.

Wipe the outside rim of the tumbler dry with a paper towel and place the lid on top. Turn the tumbler on. Let it run for seven days, checking periodically to ensure the tumbler is running properly.

Turn off the tumbler. Empty its contents into a strainer positioned over a plastic bucket. Rinse the stones with water. Do not pour the mud down the drain. Dispose of it in your trash or the yard.

Examine the stones, setting aside any with cracks or pits. These can be broken and run through the coarse grind again later to improve them. Thoroughly clean the tumbler, lid and stones with water.

Repeat Steps 2 through 6 using the appropriate amount of 120/220 Fine Grit for the tumbler size -- for example, 3 tablespoons to a 1.5-pound tumbler and 4 tablespoons to a 3-pound tumbler. Keep the barrel 2/3 full, adding plastic pellets, if needed, to fill the tumbler to its minimum.

Repeat Steps 2 through 6 with the 500 Grit Pre-Polish, following the same guidelines as before. Use the appropriate amount for the tumbler size -- for example, 4 tablespoons to the 1.5-pound tumbler and 5 tablespoons to the 3-pound tumbler. Get the tumbler and stones very clean. Coarse or fine grit grains cause scratches at this stage in polishing.

Test one of the stones to see if it is ready for the final polish. Dampen an old towel with water. Sprinkle a small amount of polish powder on top. Rub one of the stones against the towel quickly and repeatedly. Remove and examine the stone. If it is smooth and shiny, the Thomsonite stones are ready for final polishing. If not, run the stones through the extra fine grit process one more time.

Repeat Steps 2 through 6 with the stone polishing compound. Use the right amount of compound for the size tumbler being used -- for instance, 4 tablespoons to a 1.5-pound tumbler and 5 tablespoons to a 3-pound tumbler. Add enough plastic pellets to the tumbler so that the barrel is 2/3 of the way full with the stones in it. Let the tumbler run for 10 days this time. Rinse, dry and display the Thomsonite.