This Review originally appeared in the September 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. An Index to this Series of Reviews, 12 of them to date, is here. The Southland Club’s website is here and its Facebook Page is here.
In the July issue of this newsletter, I reviewed the website Geology.com. It is owned by a retired US geologist, Hobart King. King also owns Rocktumbler.com, and he himself has been tumble-polishing stones for more than 50 years. The website’s Home Page is headed up, “Rock tumblers, instructions, supplies, everything you need for rock tumbling!” A very long and informative “About Us” page starts: “You are buying from people who have done a lot of rock tumbling. We probably have several rock tumblers running in our warehouse while you are reading this. Every member of our staff knows how to operate a rock tumbler and has produced nice tumbled stones.” However, sales from the website can be made only within the United States.
Ten years ago, I discovered a well-designed video clip on Rocktumbler.com about the underfilling and overfilling of a tumbler barrel and its lessons have remained with me. And I remember more recently reading their very interesting history of rock tumbling. One of King’s articles, “What Are Agate, Jasper and Chalcedony?” is a very good discussion of these stones.
Rocktumbler.com sells high-quality rotary and vibratory rock tumblers manufactured by Thumler’s. “We don’t sell cheap plastic-barrel tumblers that make a lot of noise or imported tumblers that quit working after a few batches of rock. The tumblers we sell will last through years of proper use.” However, as explained in their “About Us” page, Rocktumbler.com sells only within the United States. This applies not only to their rock tumblers but also to their grit and polish, and their rough and polished stones (and everything else). This means that the website’s usefulness to New Zealanders is primarily the information it provides. Although we can’t buy their stones, their “Picture Identification Guide for Polished Stones and Tumbled Rocks” can answer some of our identification questions.
Their “Tumbling Library” contains lots of useful tips and ideas. “We have spent thousands of hours over the past 20 years writing an extensive rock tumbling library. If you have a question about rock tumbling, our library probably has the answer. It is loaded with articles that will help you understand rocks, understand tumblers, and improve your rock tumbling results.” There are 12 sections in the Library. The first, “New to Rock Tumbling?”, includes basic guidelines and suggestions about such issues as how long tumble polishing takes, how noisy are the tumblers, and safe and convenient places to site a tumbler. The “Instructions” section includes trouble-shooting problems, the size of stones to tumble, burnishing, and ways of cleaning barrels. Other sections include information about grit and polish, tumbling media, rotary tumbling, vibrator tumbling, rock hounding, and stone crafts.
One of the limitations of Rocktumbler.com is its focus on Thumler’s equipment rather than the Lortone and Aussie Sapphire equipment, for example, that we usually have in New Zealand. Nevertheless, at least some of the equipment information transfers usefully to all types. This is a United States-oriented site so the section on rock hounding, for example, does not address places and issues in New Zealand.
In conclusion, Rocktumbler.com is a reliable and informative website, well-presented, and very useful to home-based stone tumbling practitioners.
The next Review in this Series is not yet available. The Series Index is here.
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