The Best Beginners Guide to Rock Tumbling for Kids and Adults
The kids begged us to go gem mining during our spring break camping trip. It is a great way to spend time with the entire family and learn new things together, especially if you got the Museum of NC Minerals first. But in doing so, I didn’t exactly realize the aftermath of learning and fun this one-hour activity would turn into at home, a rock tumbling expedition.
Because we found so many gems in our bucket, I immediately came home and ordered a rock tumbler. And while waiting for it in the mail, my oldest daughter pulled out gem and mineral books from her school library. Trust me, I did not prompt her to do that.
The three of us girls have started this project with such intrigue and amusement. My oldest comes home from school every day and asks if the gems are ready. We love to see the transformations of the rocks after each stage, and the vibrate colors come out. After every stage, each of us has a favorite stone, but it seems always to change because they get more beautiful day after day. My daughter is really excited to see what pretty jewelry items I end up making with all the polished treasures.
The rocks and tumbler.
There are a few things you will need to tumble properly. The first would be the raw gemstones or picked backyard rocks. My daughter and I started this hobby when we spent the week camping in the western NC mountains. During a windy and rainy day, the family took a trip to the local gem mining shop. We purchased a large bucket of rocks and gems and spent nearly 1-1/2 hours sifting through and picking out all the pretty colors. It was great family time but also great with all the precious gemstone we found. The countless rubies, emeralds, sodalite, citrine, amethyst, topaz, clear, rose, and smoky quartz, aventurine, sapphire, tourmaline, and aquamarine was awe-inspiring.
Next, you need a good rock tumbler for your rock tumbling. I purchased NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit online from Amazon. This little rock tumbler is small, compact, and straightforward to use. This model is also perfect because it has a timer that you can set the number of days you want to tumble and then it shuts off when finished. I have found it to have great reviews online.
All about the grit and polish.
The final material needed is the grit added to the tumbler along with the rocks and some water. There are typically three types of grit and one polish material that is used in the entire rock tumbling processing. The NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit comes with single packs of each type. But if you want to tumble more rocks than what they give you, then you will need to purchase more. There are many other online companies that you can purchase the grit, or you can buy NATIONAL GEOGRAPHIC Grit Refill for Rock Tumbler in larger tubs.
The grit is an important part of the tumbling process. Grit is a silicon carbide powder where every step is a different size going from course pieces to a powdery substance to a polishing component. Silicon carbide grit is very hard. It is much harder than the rocks that most people tumble. On the Mohs Hardness scale, silicon carbide has a hardness of 9 to 9.5 while commonly-tumbled rocks such as jasper, agate, quartz, and petrified wood have a Mohs Hardness of about 7. This means that silicon carbide grit can easily abrade the rocks that most people tumble.
Grit #1 is a coarse grit that will round out all the edges of all the gems and stones. The next stage is grit #2 which typically is a medium-size silicon carbide particle that cleans up the rocks from any other unwanted calcium or other rock particles stuck to the sides of the gems or stones. Grit #3 is a pre-polishing size and again smaller than 1 and 2. And lastly, the polishing portion which is typically an aluminum or tin oxide. This gives all the rocks, gems, and even petrified wood a beautiful shine.
How to rock tumble your gems and rocks.
Gems picked through and collected but not washed.
First, a good step, after gathering your stones and rock tumbling equipment, is to set all your gems and stones in a large bucket of hot soapy water. If yours is like ours they will need a good bath. I like to use dish soap, let the rocks soak for about ten minutes and then scrub with a scrub brush to get the remaining dirt off. Don’t use vinegar in the wash because it is an acid and can adversely affect the outcome of your gems.
Gems soaked and scrubbed in hot soapy water. The colors all come through and gems are more recognizable.
There is a vast difference between the gems we collected and after a good bath. You can see the colors come out in the rocks after scrubbing off the dirt and loose calcium. That was the easy step.
Now the next step would be to trim, grind, and cut the stones into shapes that you want. That step is not for beginners and will be talked about in another post. For now, we will go right into tumbling.
I pulled out the smaller stones that really couldn’t be properly ground or cut from my pile. You want to gather enough stones that would fill your barrel to about 1/2 to 2/3rds full. It is important that you follow that step. You need enough rocks to rotate and knock into each other. If you don’t have enough, then you need to add a filler or rocks that are not necessarily wanted. Next, I weighed the number of rocks or gems. You need to weigh them because this will determine the amount of grit used.
Visual on how much water to fill up along with the stones and grit.
Fill the barrel back up with your weighed rocks and the first course, grit #1. Depending on the type or where you got the grit will depend on the amount to add. But for the brand I have suggested above you need to use two tablespoons per pound of rocks. Then fill the barrel with water just above the rocks. Don’t fill the entire barrel with water. Now set the number of days you want to tumble. Grit #1 should rotate for about five days, grit #2 & 3 for seven days each, and grit #4 should go the longest at about ten days. The longer for the polishing stage, the better the results.
More about tumbling rocks.
When you take out the rocks after each stage, you will find your gems ins a grey thick slurry mixture. Be sure to rinse out a couple of stones before emptying out all the contents. If you don’t like the results, then throw the rocks back into the barrel and turn on for a few more days.
If you like the results, then pour out the rocks and slurry mixture from the rock barrel. Do not pour the silicon carbide slurry mixture down the drain. It is not good for your indoor plumbing. Pour it outside in the yard that is what I do. Rinse the rocks and barrel well with water. It is important not to have any grit particles from the last stage transferred into the next stage.
