Rock tumbling is a great hobby, especially for kids. It is not too expensive but it is very noisy!
WHAT EQUIPMENT DO YOU NEED?
A rotary tumbler. This is basically a drum which turns round and round to polish your stones.
HOW DOES IT WORK?
The basic idea is that you put some small mineral samples in the tumbler, turn it on and have it spin for a week. Yes, a week! All those pieces, banging into each other are going to start chipping off edges and start to round your samples off. Now of course there are some tricks we need to employ to get the best results. You need to fill the tumbler around one third of the way with water. This helps to wash away pieces. You are also going to add grit, which is actually a fine metal powder. Think of it as powdered sand paper.
SO WHAT'S THE PROCEDURE?
1. Add your samples and water to the tumbler, and add a coarse grit. Let it go for a week. At the end of the week, you need to drain the contents and the clean the tumbler and the samples so that no grit remains.
2. Repeat step number one, this time with a medium grit
3. Repeat step number one, this time with a fine grit.
SO HOW COME THEY ARE NOT SHINY?
Well, by now the samples are nice and round and smooth. Wet them and they will look beautiful. As soon as they dry, they are dull again. We need to polish them so they stay shiny. You basically used the same procedure, putting the samples and water in, but no grit. This time we are going to add a powdered polish. This will bring about the shiny look you want. But we don't want the stones banging into each other, because that could result in scratches, so you need to add something to cushion the stones. The simplest material is small plastic beads.
SO WHAT CAN I PUT INTO THE TUMBLER?
You have two choices for samples: ones that you have found and ones that are purchased, also known as tumbling rough. In either case, a quick geology review is necessary. Rocks are made of minerals. Some rocks are made of one mineral, while most are made of two or more. A property of minerals that must be considered when tumbling is hardness, which is not if a mineral breaks, but is a measure of how easily it can be scratched. Hardness is measured on a scale that ranges from the softest minerals with a hardness of 1 (such as talc) to the hardest with a hardness of 10 (diamond). You can only tumble minerals that are at least 5 or more on the scale. Any softer and there will be nothing left when you open your tumbler. Rocks, because they most often are made of several minerals should not be used.
If you want to use your own samples, the best place to go is a rocky beach. If they are there, you know they are tough because they have already survived the tumbling by surf.
SO WHERE DO I GET THE GRIT AND TUMBLER AND ROUGH?
Simply go online and search for tumbling or lapidary supplies. There are lots of great dealers out there to get you started. Good luck, have fun and find someplace well insulated to set it up so it doesn't keep you up all night!