Rock Tumbling

My son, Jacob, has always been a rock hound, and for his birthday we got a very nice rock tumbler, a Lortone QT66. I have never been too interested in rocks but found myself in charge of our inaugural tumble.

Rock tumbling takes time — we chose a basic timeline of four stages, each lasting a week, and each stage using ever finer grinding and polishing powders.

We used a premixed package of tumbling stones along with many additional ones, including agates, from Jacob’s collection.

After one week:

You can already see the edges smoothed down (unfortunately I didn’t photograph the stones in their natural state).

After two weeks: looking much smoother and a lot of material has been ground away. If you look carefully you can match stones between each image. My favorite stone is the white stone with black lines approximately center in the above image.

After three weeks: the stones are ground down about as much as they’ll be, but the now smooth surfaces are starting to polish. There’s my favorite, on the right side, starting to get that glassy look.

Final stage. In the previous photos, the rocks were wet, but in this shot all the stones have been dried. They still look wet and shiny — the point of the last two weeks of polishing.

They’re not perfect: some stones polished unevenly, others have flaws (recesses) that never received any grinding or polishing. Even so, a few of the rough stones came out of the process shiny, translucent, and nearly flawless.

I’m already looking forward to starting the next batch, I’ve picked up ceramic tumbling media which should result in better grinding and polishing.

I’ve also found some guides with better information on how to choose stones and which types and sizes to group together.