The Comprehensive Guide To Shopping For A Rock Tumbler
Rock tumbling can be a really enjoyable activity. Perhaps the best part about it is that people of all ages can take part in it. At the same time, it is quite educative.
Plus, you don’t need a lot of things to get started – a reliable rock tumbler, a few rocks and a bunch of accessories and you’ll be on the right path. You can use the rocks to create unique pieces of jewelry, make decorations, crafts, or just for fun.
However, you might want to find out more on the topic beforehand, and this is the purpose of this guide – to offer you the information you need to take up this hobby.
In This Article You Will Learn...
What Are Rocks And How Are They Formed?
Since Earth is a terrestrial planet, this means that it is separated into layers, which have specific rheological and chemical properties. It is in the lithosphere where rocks are formed, and all the changes take place.
Essentially, the forming process depends on the type of rock; and there are three primary types of rocks, namely igneous, sedimentary and metamorphic. Considering that each has a distinct origin, the formation process differs.
Igneous Rocks
To start with, igneous rocks occur as melted rocks cool and, thereafter, solidify. For the most part, melted rocks derive from magma – which is melted rock that is found underneath the Earth’s surface.
At the same time, melted rock might come from lava. This is the result of a volcanic eruption. Some classic examples of igneous rocks include scoria, granite, pumice, and obsidian.
For instance, pumice is the lava derived from melted rock, water, and trapped gas expelled from a volcano during a volcano eruption. Since the ejected material goes through the process of cooling and depressurization really quickly, part of the trapped gas escapes. That leaves gas bubbles and holes in the solidified material.
Sedimentary Rocks
Moving on, sedimentary rocks result from materials and soil components that are cemented into a single rock layer. With the passing of time, the number of materials that settle on the latter layer increases, which leads to the formation of another layer of sediments.
The lower layer experiences significant pressure, due to the weight of the upper layers. This will lead to the formation of sedimentary rocks such as limestone, sandstone, conglomerate, shale, and gypsum.
Interestingly, sandstone forms as a result of the sand and depositions from rivers and beaches. You might find this rock in deltas, considering that this is where rivers flow into the ocean.
Metamorphic Rocks
The term metamorphosis stands for change. That is to say, metamorphic rocks result when other rocks on Earth have undergone extreme heat and pressure. For example, a metamorphic rock might have been sedimentary, igneous, or curiously enough, metamorphic.
The changes take place when the original rocks face extreme temperatures and pressure. Conversely, this might happen if two types of rocks are stuck in the middle of two colliding tectonic boundaries. For instance, marble forms due to the metamorphosis of dolostone and limestone.
What Is Rock Polishing Aka Rock Tumbling?
Rock polishing is the process that involves tumbling the rocks, similar to the way in which Mother Nature transforms rocks over the course of thousands of years. You require a rock tumbler device that turns the barrel round and round for weeks.
The process involves the use of grit and water. The grit is responsible for making the rocks smoother. To be more specific, the grit has to replace the sand that Mother Nature uses for smoothing and polishing the rocks.
The grit has distinct levels of coarseness; therefore, we could associate it with sandpaper. At the beginning of the process, you might want to use a very coarse grit, which will smooth the sharp edges of the rock.
Nonetheless, after a few weeks, you should replace it with a smoother grit until the final stage of the polishing process. Eventually, the rock should be matte when dry and shiny when wet.
Mohs Hardness Scale
A critical factor when it comes to rock tumbling is assessing the hardness of the rock. This is just as important as investing in the best-rated rock tumbler.
A rock’s hardness rating refers to its resistance to being scratched. However, why is this element so important? In lines with the general rock tumbling instructions, you should have the rock polished one week in coarse, one week in medium, another week in fine, and finally, a week in polish.
At least, these rules apply to the most common types or rocks – namely petrified wood, jasper, agate, and quartz. Considering that these materials feature similar hardness ratings, they can easily withstand a whole week of coarse grit.
Nevertheless, let’s say that you intend to polish softer materials such as glass, sodalite, and obsidian. In this scenario, following the general one week rule in coarse grit won’t do. On the opposite, doing so might eventually reduce the rocks to tiny particles – and you don’t want that.
On the other side, hard rocks such as topaz and beryl are worn away at a much slower pace by coarse grit. Thereupon, if you want to obtain a nice rounded shape and a smoothened surface, a week in coarse grit might not suffice.
So, how do you assess the hardness of the rock? Back in 1812, Friedrich Mohs came up with a way of testing the approximate hardness level of a rock or mineral.
Accordingly, the softest rock’s hardness level was of 1. The second softest rock was given a hardness level of 2, whereas the rock with the highest hardness level was given a rating of 10.
For example, the rating for topaz is 8, whereas the rating for marble is 3. The hardness scale developed by the renowned German mineralogist is widely popular till this day – being referred to as the Mohs Hardness Scale.
How To Determine The Hardness Of My Rocks?
If you are serious about rock tumbling, aside from picking the best rock tumbler kit, you should also be careful about the hardness level of the rock. As we explained above, this will aid you to determine the time you should direct for each grit stage.
Kits
For starters, it could be an excellent idea to get a hardness testing kit. This way, you’ll be sure that you’ll obtain the best tumbling results.
There are kits especially created to make the hardness testing as easy and accessible as possible. For example, some kits include special alloys whose goal is to assess the hardness of the minerals, according to the Mohs Scale.
On the other side, there are testing kits that incorporate some of the most commonly used minerals for hardness testing. These kits are just as handy.
Known Materials Scratch Test
Considering that you don’t have a kit at hand, there are some general tips that can be used for determining the hardness level of a rock.
Firstly, a good idea might be to use a penny, whose hardness is of 3.0. If you can manage to scratch the rock with a penny, this merely means that its hardness level is it least the same as it is for calcite – H=3.
Secondly, believe it or not, you might use your fingernail to do some testing as well. If you didn’t know until now, the hardness rating of your fingernail is 2.5 – which is a bit smaller than in the case of a penny.
Therefore, if you manage to scratch a rock by using your fingernail, this could only mean one thing: its hardness level is less than 2.5. That would mean that it is softer than calcite (H=3) and harder than gypsum (H=2).
Thirdly, another viable option would be using a steel blade. Typically, the hardness of a steel blade is roughly 5.5.
In other words, if you don’t manage to do any damage with a penny or with your fingernail, and you do succeed with the steel blade of a knife, then you know for sure that the rock is harder than calcite (H=3) and softer than orthoclase (H=6).
Common Rock Tumbled Materials
If you want to purchase the best rock tumbler for a beginner, the odds are that your knowledge of types of rocks is rather limited. This is why we’d like to briefly present the main rocks that are used for polishing.
However, before we do that, we should tell you what makes a good rock for tumbling. For one thing, it should be hard; softer rocks are rather challenging to polish. As a rule of thumb, rocks whose hardness level ranges from five to seven are most suitable for polishing.
Meanwhile, those that are harder than seven are specifically sturdy. This means that the abrasives will cut them really slowly. So, even if you pick the best rock tumbler, you might not obtain the results you want.
Agate
Without a doubt, agate is the most common rock used for tumbling. It is a translucent material, and it can be found in a wide range of colors. Generally speaking, agate features natural color decorations of clouds, eyes, plumes or mossy formations – this is, in fact, what makes this rock one of a kind.
These specific patterns occur due to the crystallization history of the rock cavities. Another considerable factor is represented by the various types of impurities that are transferred by ground waters.
Thanks to its innate translucence, this grants it an internal glow that outlines its beauty. If you use the best vibratory rock tumbler to polish it, you’ll soon realize why it’s such a popular pick for many hobbyists.
Agate forms when groundwater deposits levels of minerals in rock cavities. To be more specific, it is in the air pockets in andesites, rhyolites, basalts, limestones, and shales where agate might develop. As a rule of thumb, agate tends to withstand weathering better than the rocks in which it is enclosed.
Jasper
Moving on, jasper is another popular choice, as it can be found in a multitude of colors. Generally speaking, though, jasper occurs in shades of gray, white, and earth tones such as brown, orange and yellow. Nonetheless, on some occasions, you can see it in distinct shades of green.
You should know that jasper can withstand a bright polish, being among the most durable polishing materials.
Interestingly enough, jasper is a sub-variety of microcrystalline quartz. Nonetheless, it is not translucent; it has an opaque finishing, being described as semi-translucent. We would recommend beginners or children to start off with jasper, as it is easy to work with it.
Petrified Wood
Petrified wood is definitely worth noting, as well. This type of rock results when woody materials are submerged in an ash fall. Alternatively, this rock could develop as other sedimentary deposits that are afterward replaced by carbonate materials transported by groundwater.
Many times, petrified wood features designs that resemble growth rings, cell walls or other beautiful plant structures.
Even though it would be safe to say that petrified wood isn’t especially abundant, it might be colorful. At the same time, the fact that it preserves different plant structures definitely makes it unique and appealing to rock polishing enthusiasts.
Quartz
And lastly, quartz is, without a doubt, the most abounding mineral present in Earth’s crust. Most of the time, it is found in unusual, yet delightful shapes. It is transparent and the variety of color hues is diverse, which is one of the features that make it so appealing altogether.
Rock tumbling adepts often choose clear quartz, amethyst quartz, rose quartz, or smoky quartz.
Among the most beloved subcategories of quartz, the ones worth mentioning are aventurine and the tiger’s eye. Aventurine is a type of quartz that features inclusions of iron oxide, mica or other minerals. These specific inclusions grant the rock a glittering, shiny appeal when viewed from a given angle.
As for the tiger’s eye, it develops if crocidolite is substituted by quartz. The result is a rock with a fibrous texture, which is distinguished by a silky gloss.
Where Do I Find Rocks To Polish?
There’s no use to look for the best rock tumbler reviews if you don’t have any rocks to polish. And this leads us to a commonly met question: where can you get rocks for this purpose?
Order Online
Essentially, the easiest and most convenient option is ordering them online. The good thing is that almost everything can be ordered online nowadays, which can seriously make our lives easier. This applies when you shop for the best rock tumbler, or when you look for rocks.
Some stores even provide 2-day shipping – so, if you want to get started ASAP, you don’t have to go into the wild and hunt for rocks that seem suitable for tumbling.
Hunting In Nature
The second alternative is looking for them in nature. However, you must know where to look if you want to get any results. Otherwise, you might look in vain.
At the same time, the reason why many people enjoy rock tumbling is the exact process of looking for rocks in natural environments. This can be really thrilling; but, once again, it depends on you.
As we noted beforehand, agate is one of the most popular choices because it’s rather easy to work with. Additionally, you are likely to find it in the Western States – namely Arizona, Oregon, Montana, Wyoming, Michigan and South Dakota.
You should look for them in lakes shores and coastal areas. You might get lucky in the proximity of places that have a past with volcanic activity.
Ideally, you should go to rocky beaches when the tide is low. At times, you might find the agate lying right on top. Still, this isn’t the norm; you might need to start digging since they might be buried among other rocks, as well.
Another type of rock that is fairly easy to hunt is jasper. Once again, you might find it in the Western States in the United States, namely California, Oregon, Washington, Idaho, Arizona, Utah, Arkansas and Texas.
Notwithstanding, as a rule of thumb, if you want to increase your chances of success, you might want to get a guidebook for your area, to check what rocks you’re likely to find. Getting a guidebook might also provide a range of helpful tips on tactics you should use.
How Do I Find Out If My Rock Is A Good Candidate For Tumbling?
Tumbling the first rock that crosses your path isn’t something you can do. In fact, there are specific types of rocks that are compatible with a rock tumbler, while others aren’t. It’s up to you to distinguish between these two categories if you want to make the most out of this hobby.
We’ve already mentioned beforehand that a good tumbling rock should be hard. Therefore, regardless of the way in which you plan on assessing a rock’s hardness level, make sure you do that before placing it in the rock tumbler.
Secondly, another important consideration is to ensure that the rock is dense, without pore spaces and fractures. That’s because pores capture small particles of grit. This means that those particles will be further transferred from one stage of the tumbling process to another one – and you don’t want that.
The contamination of several types of particles will end up ruining the polishing stage. Take it from us – nothing is worse than a beautifully polished rock with coarse grit scratches.
Fractures might lead to other complications. Eventually, they might lead to the breaking of the rock in the tumbler. Plus, the sharp edges that might remain inside will end up scratching other rocks.
Lastly, good tumbling rocks should have a smooth texture, as well. If the surface is grainy or gritty, perhaps you should pick another rock. What is more, if the rock produces debris when rubbed with another rock, it will eventually release grits that might scratch all the rocks you have in the barrel.
How Long Does Rock Tumbling Take?
This depends. It might take two weeks to two months, depending on numerous factors. Of course, the type of rock tumbler you use plays a crucial role in the equation. Essentially, the rock type is just as important.
For example, if you use a rotary tumbler, the polishing process might take from four to eight weeks. Generally speaking, rotary tumblers use a four-step process, as follows: coarse grind, medium grind, fine grind – referred to as the pre-polish step, and, lastly, the polish. Each step lasts a week – at the very least.
On the other side, vibratory tumblers are much quicker than rotary devices. The process may take from one to two weeks, total. It also depends on the rock. Considering that this type of device is much quicker, you might wonder why one should consider getting a rotary tumbler.
For one thing, vibratory tumblers are much pricier than their rotary counterparts – they cost up to 50 percent more. At the same time, a vibratory tumbler smoothens the rock, as opposed to rounding it similar to the way in which a rotary unit does.
As you can see, personal taste and preference is another thing to bear in mind. If you prefer rounded rocks, you should go for a rotary unit. On the opposite, if you are keen on angular rocks, and you want the process to be as quick as possible, a vibratory rock tumbler will do.
Conclusion
On a final note, if you’ve reached the end of this article, you should have the background information required for getting a tumbler. Make sure you read our upcoming article that focuses on answering the question “what is the best rock tumbler?”.
We’ll also introduce you to the best rock tumbler for sea glass, as well as the best unit for children and for beginners. That being said, make sure you check our rock tumbler buying guide if you want to make an informed purchase!
