As an Amazon Associate, I earn from qualifying purchases with no additional costs for you.
While nature can certainly create some stunning rock formations, recovered rocks are initially quite different from those displayed in stores and collections. Rough rocks go through an entire process to become the shiny, magnificent, and desirable stones seen by the public.
Agate, Jasper, Quartz, Aventurine, Tiger’s Eye, Obsidian, Howlite, Petrified Wood, Amazonite, Moonstone, Sunstone, Labradorite, Sodalite, Unakite, and Dalmatian Stone are good rocks for tumbling. This is due to their density, Mohs hardness, and physical properties.
Some rocks don’t have ideal physical properties for rock tumbling, but many are perfect for this process. This article lists some of the best rocks for tumbling and details which qualities are required for tumbling to ensure you end up with some gorgeously glossy stones.
If you want to check out the best rock tumblers, you can find them here (Amazon link).
What Rocks and Minerals Are Good for Tumbling?
There is something incredibly satisfying about witnessing such a drastic transformation, and the process by which a rough rock is transmuted into a smooth, shiny stone gives many people an abundant sense of achievement.
Apart from having the joy of owning a lovely collection, this accomplishment is often the main motivation for this hobby.
High-quality rough rocks are needed to achieve high-quality results. Rocks that are permeable or cracked will not produce an attractive tumbled stone.
Low-quality or granular textured rocks also have a chance of shedding fragments and scratching surrounding rocks, so these are carefully modified beforehand or avoided completely.
The rock tumbling process is understandably harsh on the rocks, and therefore, the rocks must have durable physical properties to withstand the process.
Other than the overall quality of the rock, one of the most important factors when selecting rocks to tumble is its hardness.
Most tumbler grit is made of silicon carbide, one of the hardest artificial materials, and the selected rocks need to withstand this.
The entire batch of rocks going into the tumbler barrel also needs to be similar in hardness, as a large difference in hardness could damage the softer rocks.
A batch of softer rocks can be used, but the timing of each stage will need to be shortened and should be more carefully monitored.
A batch of too hard rocks will result in the opposite effect and take extremely long to smooth down. The coarse grit stage is often prolonged for the best results for very hard batches.
In addition, factors like consistency and quality also have an impact on potential outcomes. As a result of these conditions, the most ideal tumbling rocks do not have fractures, voids, or wide pores but are dense, smoothly textured, and have a Mohs hardness of around 7. These rocks are the best options to achieve great results.
Agate
Agate is a microcrystalline variation of quartz and is undoubtedly the most popular option for tumbling. This is due to its hardness, density, natural smoothness, how commonly it is obtained, and how well the rock responds to the tumbling and polishing.
It generally forms when groundwater deposits minerals in rock cavities, fractures, and bedding plane separations. It can, therefore, be found in abundance around stream beds and dry washes in some geological locations.
This translucent material carries an array of interesting visual qualities, including eyes, bands, cloudy spotting, spirals, and various colorful patterns.
Its unique interior glow and its translucence and patterns give this rock a bright, distinctive, and aesthetically pleasing appearance once polished.
Agate is one of the best options for tumbling, as each rock is exclusive, making it easy to build up a visually diverse tumbled rock collection.
TIP: Agates are one of the best rocks for tumbling and one of the most favorite. The best places where you can find them are in this article:
Where Can I Find Agate Rocks? Best Places in the US & World
Jasper
Jasper is another variety of microcrystalline quartz and is exceptionally popular due to its wide range of colors, durability, and density.
It can be opaque to semi-translucent and forms in various fracture fillings and replacements.
This beautiful rock occurs in an array of monotone colors, such as white and shades of grey. It also forms in earthy tones like red, yellow, orange, and brown. This color palette is complemented by the rock’s swirls, spirals, and clouds of contrasting tones.
It is relatively hard and quite suitable for the tumbling process. The natural undertones of the rock create a lovely foundation for bright and lustrous polishing, and the use of Jasper could result in a large visual variety in your collection.
TIP: Jasper is a really beautiful rock that can be found in a lot of locations in the United States. Find out the best ones in the article below:
4 Best Locations for Finding Jasper Rocks Near Me (USA)
Quartz
Quartz is the most plentiful mineral resource that forms within the Earth’s crust and comes in various variations. Some of the most commonly used types of crystalline quartz include amethyst, clear, white, rose, yellow, and smoky quartz.
These kinds of quartz are ideal for tumbling, as they are hard, durable, and relatively easy to smooth down. Quartz ranges from transparent to translucent and receives bright polish extremely well.
TIP: Quartz is a common mineral all around the world. You can find it in many places, for example on the beaches. If you want to learn some tips on this topic, feel free to read this article:
Can You Find Quartz on the Beach? It Depends on How You Look
Aventurine
This variety of quartz commonly forms in green tones, is a particularly popular option for rock tumbling, and is sought after by jewelry makers. It is dense and durable for the tumbling process and has a range of interesting visual qualities.
Aventurine contains inclusions of mica, iron oxide, or other minerals, which produce a different effect than other quartz variations.
The presence of these minerals has a special orientation, which results in a shimmery, glittering appearance when observed from particular angles.
Tiger’s Eye
Tiger’s eye is another popular tumbling material due to its suitable physical properties. The rock is similar to other quartz variations but forms when quartz replaces crocidolite.
This results in a rock that is fibrous in texture and intermingles with surrounding light to create a silky luster known as chatoyancy.
Obsidian
This volcanic rock often occurs on the margin of the lava flow and has been a miraculous enigma for the public since it was discovered.
It’s formed when molten lava rock material cools so rapidly that it solidifies into a shapeless glass instead of crystalizing into structured mineral forms as other rocks do.
Obsidian is not as easy to tumble as other rocks, such as quartz. This is due to the fact that it has a Mohs hardness of 5 – 6 instead of around 7, which could result in bruising and chipping during the tumbling process.
However, with the use of ceramic media or plastic pellets for cushioning and some adjustments in tumble timing, you could end up with a stunning dark stone in an array of black, brown, red, and other dark tones.
The swirls and nodules are reminiscent of its molten lava origins, and some specimens called ‘snowflake obsidian’ feature white cristobalite spherulites, giving it a black-and-white spotted appearance.
TIP: Obsidian is among the most prized rocks in their collections that all rockhounds want to have. Find out the best locations where to find obsidian in the article below:
Finding Obsidian: 6 Best Locations Near Me (United States)
Howlite
Howlite is another suitable rock for tumbling. The hardness and density make it an ideal choice for smoothing and polishing.
However, this rock is not as popular, as it is fairly plain and bland in appearance. Howlite usually forms in shades of white, which is considered relatively uninteresting for most people, particularly compared to some of the more popular tumbling stones.
As a result, Howlite still tumbles frequently but is often dyed to resemble turquoise to enhance its appearance.
Petrified Wood
Although this material has been called petrified ‘wood,’ it is, in fact, a kind of rock. This rock is formed when woody material is submerged in sedimentary deposits like ash fall and is then replaced by siliceous or carbonate materials transported by groundwater. Its properties are ideal for tumbling since it’s dense and relatively smooth.
Although petrified wood does not necessarily display a range of bright colors or patterns, it is unique because it can often display cell walls, bark, growth rings, and relative plant structures.
Petrified wood is not easy to come by and does not have an overtly exquisite appearance. But, the originality of having a satisfyingly smooth stone that exhibits preservations of plant structures is incredibly alluring to many people.
TIP: Petrified wood is a beautiful plant fossil that can take on many colors and give a certain sense of awe. Find out where to find petrified wood in the article below:
6 Best Locations for Finding Petrified Wood Near Me (USA)
Amazonite
Amazonite is a rock containing microcline feldspar minerals and is named after the Amazon River.
Although it is not generally found in that area, this rock forms in various green shades, such as pastel, deep, and blue-green, resembling the shades of green that run through the Amazon River.
Many rocks containing minerals from the feldspars group are ideal for tumbling, as they respond well to smoothing and polishing.
However, feldspars can break during tumbling due to their planes of cleavage. These can become weak points that are vulnerable to damage if the tumbling process is too rough.
Much like obsidian, the successful tumbling of these rocks can be rewarding, and the process can be assisted by using plastic pellets and ceramic media for cushioning.
Moonstone
This rock can be either an orthoclase or albite feldspar. The rock has similar physical properties to most feldspars, is relatively hard, and polishes well.
Moonstones form in various colors, such as white, pink, grey, green, orange, and brown, each occurring in various shades. The stone has a natural glistening opalescent sheen and exhibits an interesting response to light known as adularescence.
TIP: Moonstone is a popular type of stone for décor and jewelry pieces. Check out the simple guide on tumbling moonstone in the article below:
Can You Tumble Moonstone? Try These 4 Simple Steps
Sunstone
Sunstone is a fascinating plagioclase variation of feldspar, and its name stems from its unique visual appearance. The mineral composition of sunstone includes minuscule copper flakes, which cause an interesting effect when moved under the light.
This is due to the copper flakes’ special orientation, which reflects light within the stone, resulting in a copper-colored flash. This sought-after rock could be a novelty treasure if tumbled carefully according to feldspar requirements.
Labradorite
Labradorite is another variation of plagioclase feldspar that is a popular option for rock tumbling. This is due to the effect that its natural qualities have when brightly polished.
The rock displays the phenomenon known as labradorescence, which describes a specific reaction to light. The mineral composition of this material results in a play of colors, including shades of electric blue, green, and yellow when moved under the light.
Sodalite
Although sodalite is rare, it’s valued for its hardness, durability, and beautiful sheen when polished. It has a Mohs hardness of approximately 6, which is still fairly suitable for tumbling.
The rock frequently exhibits white patterns formed by other minerals distributed in the rock, such as nepheline. These white swirls complement its rich blue color.
Unakite
This distinctive igneous rock has been named after the Unaka Mountains in North Carolina, where the stone has been quarried since the mid-1990s.
Unakite is unique in appearance, as it comprises pink and green mineral grains. Its combination of orange, pink, yellow, and green mineral grains makes up its final visual qualities.
Unakite contains orthoclase, an orange-pink mineral of the feldspar group with a Mohs hardness 6, making it a suitable option for rock tumbling. The yellow-green mineral is called epidote, which is a rare mineral found in a low amount of igneous rocks.
Dalmatian Stone
Also known as Dalmatian jasper, this rock is a monochrome igneous rock found in Chihuahua, Mexico. Although this rock is not a type of jasper, the name stems from its appearance, as it resembles the spots of a Dalmatian dog. It was thus later renamed Dalmatian stone.
These rocks form in a range of neutral shades, from light brown to bright white, with varying sizes of black spots.
It’s an extremely popular rock for many people who are beginning rock tumbling as a hobby, as it tumbles quickly, forms a desirable rounded shape in the tumbler, and polishes well into a subtle level of luminosity.
TIP: Loading your rock tumbler with rocks and grit can be challenging. Check out the complete guide on loading your rock tumbler in the article below:
Rock Tumbler Loading: How Much Grit & Rocks Do You Put In?
Can You Put Crystals in a Rock Tumbler?
You can definitely tumble crystals. But it’s still important to understand crystal properties to have a successful tumble batch, as they differ from rocks.
A crystal is a solid mass with an organized structure, with very particulate positioning and repeating arrangement of atoms that form a three-dimensional pattern known as a crystal lattice.
Crystals are present in many solids but are often cryptocrystalline or microcrystalline, making them a microscopic contributing factor to the formation, as opposed to a macrocrystalline crystal visible to the naked eye.
A crystalline structure makes a true crystal identifiable since it’s unique and specific to each mineral variety.
Rocks are usually composed of at least two varying minerals, and these rock-forming minerals can create igneous, sedimentary, and metamorphic rocks.
Since rocks are made up of minerals instead of crystals, they do not have a crystalline structure. Some of the most popular crystals include Amethyst, Azurite, Celestite, Citrine, Fluorite, Garnet, Malachite, Pyrite, and Rhodochrosite.
Many cryptocrystalline and microcrystalline variants of Quartz are also debatable’ crystals.’ All of these can be tumbled, but each crystal must be quality-checked carefully, and some adaptations to the process may be required for the best results.
BTW: Do you want to know more about rock and mineral identification? The books listed below are the best ones you can find on the internet (Amazon links):
- Smithsonian Handbooks: Rocks & Minerals
- Gemstone & Crystal Properties (Quick Study Home)
- Ultimate Explorer Field Guide: Rocks and Minerals (National Geographic Kids)
How Much Grit Do You Put in a Rock Tumbler?
Rock tumbling involves using a rock tumbler, water, and tumbler grit varying in coarseness. Combined with water and the motion of the rock tumbler barrel, this grit scratches the surfaces of the rocks, resulting in smooth, rounded edges and surfaces.
This process consists of five stages – coarse grind, medium grind, fine grind, polishing, and burnishing. Different types of tumbler grit are used in each grinding stage, and it’s crucial to ensure that the correct grit is present in each corresponding stage.
Each rock, the tumbler barrel, and the tool are cleaned between each stage to avoid cross-contamination of grit, rock particles, and granules.
In each tumbling stage, two tablespoons of grit are used for each pound of rock – first coarse, then medium, then fine grit. The grit is replaced with rock polish within the polishing stage, and ivory bar soap is used within the burnishing stage.
It’s, therefore, essential to weigh the rocks before tumbling to calculate the required amount of grit, rock polish, and ivory bar soap for each stage within the rock tumbling process.
TIP: Rock tumblers use various types of grit in the multiple stages of the rock tumbling process to shape, smooth, and polish the stones. Find out more in the article below:
Rock Tumbling Grit: Usage, Types, Disposal & Substitutes
Can You Tumble Rocks without a Tumbler?
The process is more time-consuming than difficult, as various types of machines are generally used, namely rock tumblers and different kinds of rotary tumblers.
However, creating beautifully polished rocks and gemstones without machinery is still possible.
You can smooth down and polish rocks by hand using a bucket, hot water, soap, an old toothbrush, protective eyewear, gloves, a handheld rotary tool, stone polish, and rough rocks.
You will also need the coarse, medium, fine, and ultra-fine sandpaper to replace the grit used in a tumbler.
This can be done by imitating the traditional rock tumbling stages, cleaning the stones by hand, and grinding the stones with a handheld rotary tool.
The rocks will need to be individually sanded down with moistened sandpaper, which is compatible with the hardness of your rock and stage of smoothness. They will then need to be polished by hand using a heavy fabric such as denim until they begin to shine.
There are plenty of popular and suitable options for rock tumbling, all of which require knowledge and an abundance of patience. Some of these rocks are more easily attainable, and some require a slightly different approach to the tumbling method.
Regardless, the achievement and reward at the end of the process are invaluable, and holding these smooth, glistening treasures under twinkling lights will certainly make the process worth it.
TIP: Actually, I wrote a step-by-step guide on how to tumble rocks without a rock tumbler. Find out how to do it in the article below:
Can You Tumble Rocks Without a Tumbler? Step-by-Step Guide