Rock Tumbler

National Geographic Professional Rock Tumbler back of box

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Turn Rocks and Water Into Shiny Stones

National Geographic Professional Rock Tumbler back of box

  • What: National Geographic Rock Tumbler Kit
  • When: 7 years and up
  • Why: Educational, easy to operate
  • Where: Amazon

Have a rockhound on your hands? Want to show them the power of a little bit of water and movement? National Geographic’s Rock Tumbler can turn plain rocks into things of beauty, mesmerizing your child in the process.

National Geographic Hobby Rock Tumbler on Amazon

This rock tumbler comes with everything kids need to polish one set of rocks. It includes an insulated tumbler to help reduce noise, one bag of rocks of various types, four bags of polishing grit, a sifter, and instructions. Once kids polish all the rocks included, they can use any remaining grit to turn more ordinary rocks into sparkling rounded stones. 

National Geographic Rock Tumbler rocks loaded into cylinder with Step 1 grit before tumbling
Add rocks, grit, and water, and let the tumbler do its work.

Kids add the rocks, polishing grit, and water to the tumbler, then plug it in and watch it spin. Each stage takes a different number of recommended days to get the most shine. The first grit takes three to five days in the tumbler. Grit number two takes six to eight days, as does grit number three. The fourth level of grit suggests seven to ten days for the optimum shine. After each stage, use the included strainer to rinse the rocks and remove all the grit dust, preferably outside as the grit can damage household plumbing.  If you want to go the extra mile, you can do a fifth round of tumbling with gem foam for an additional three days to finish the process. You can also adjust the speed on this tumbler, so you can spend less time in the earlier smoothing phases and get through the entire process quicker. 

National Geographic Rock Tumbler in action with days and speed indicators
This rock tumbler takes days to complete each stage, and makes plenty of noise.

This rock tumbler isn’t for the impatient type of kid. If your child has a short attention span, this science experiment will not be ideal for them. My son got his tumbler as a gift back in September. It’s almost November and those rocks are still tumbling. That being said, one round of tumbling makes enough difference to see some serious results, though that still takes at least three days. A word of warning to parents as well. Rock tumblers make noise – a lot of noise, around the clock. We stuck ours in a detached garage. I cannot imagine having it in the house unless you want oodles of white noise and to talk over it anytime you’re in the same room.

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