To the untrained eye, a rock is just a rock. To rock tumbling enthusiasts however, a rock is much more, and the potential to create something beautiful from something mundane is what attracts so many people to the hobby.
Beginners may be wondering what kinds of rock they should be tumbling.
While rock tumbling kits will often include a few different types of rocks and gemstones to get started on, part of the fun is finding your own rocks to tumble, and opening the barrel at the end of polishing to see what it is you have created.
The Most Popular Types of Rock
Agate is by far the most popular choice for tumbling and is readily available online.
Agate pieces are often beautifully decorated, while the natural translucence gives it a glow you don’t get from other rocks. It’s generally very hard and resistant to weathering.
Another popular type is jasper. This is usually available in white, grey and earthy tones making it fantastic for more minimalist and dainty jewellery. It accepts a bright polish and is very durable but unlike Agate, it is opaque.
Quartz is another great choice for tumbling. It’s transparent to translucent and available in a range of beautiful colours.
There’s various types of quartz, including Aventurine, Tiger’s Eye, Amethyst Quartz and Rose Quartz, all of which can produce lovely gemstones and jewellery.
While these are undoubtedly the most popular type of rocks for tumbling, this list is by no means extensive.
There’s a whole bundle of other types of rock which tumble beautifully. Our favourites include Petrified Wood, Obsidian, Amazonite, Moonstone and Sunstone.
The Best Qualities
If the names of the rocks mean nothing to you and instead you’d rather find rocks based on size, shape and colour then it’s worth knowing what qualities to look out for.
It’s important to note that having just one unsuitable rock won’t solely mean that rock doesn’t polish or smooth well, it’ll also affect the rest of the rocks in the batch.
To save time, effort and possibly your barrel, try to find rocks with these specific qualities:
Good rocks for tumbling tend to be very hard, between about five and second on the Mohs Hardness Scale.
Too soft and they won’t polish very well in the tumbler, while too hard can mean the abrasives cut them too slowly.
It’s important that the rocks don’t have pore spaces or fractures. Spaces in the rock will trap particles of grit and won’t yield a good polish.
Fractures within the rock will cause the rock to break inside the tumbler, while the sharp edges will scratch other rocks inside the tumbler.
While rocks with lots of fractures can be broken into pieces before you put it in to the barrel, rocks with pore spaces shouldn’t be used.
Good tumbling rocks generally have a smooth surface and are not gritty or grainy. This makes them much easier to polish.
Rocks with grit or particles that get released when you rub them together will scratch the other rocks inside the tumbler.