Tumbled Stones Often Called Crystals
Tumbled stones are rocks and minerals that have been tumbled in a rock tumbler to produce smooth, rounded and highly polished stones. The process begins by placing stones of a similar size inside the barrel of the rock tumbler which is then filled with water, sand and coarse grit. The barrel then slowly rotates which gradually causes the stones to lose their rough edges and take on a more rounded shape.
The coarseness of the grit determines the smoothness of the tumbled stones. Initially a very coarse grit is used but is then replaced with medium and then fine grit. The grit works in the same way as sandpaper, the finer the paper the smoother the end result. The final stage of the tumbling process is to polish the stones which is done using grit that's almost as fine as powder.
The length of time that it takes to produce perfect tumbled stones can vary from a few days to months and is dependent on a number of factors. These include the size of the rock tumbler which could be a small amateur machine or something on an industrial scale, the size and hardness of the rocks and minerals being tumbled, the quantity inside the barrel and the type of grit that's being used.
Using a rock tumbler to produce tumbled stones is simply mimicking natural geological processes. In nature these type of stones are created as fragments of rock which are laying beneath or adjacent to a body of water are gently moved back and forth. The movement caused by the motion of the water causes them to rub against each other and against sediment. Sediment is made up of small pieces of rock, minerals and the remains of plants and animals.
Over long periods of time the fragments of rock become smooth and take on a more rounded shape. We generally refer to these stones as beach or river pebbles.
Industrial sized rock tumblers at one of our suppliers
The vast majority of tumbled stones are minerals which are naturally occurring crystalline solids. A solid described as being crystalline means that it has a crystal structure or in other words is made up of crystals. This is how the word 'crystals' as in healing crystals came about. The word crystals is used almost exclusively by those with an interest in using rocks and minerals for their healing properties.
The reason I said the "vast majority" of tumbled stones are minerals is because materials like obsidian, shungite and common opal are not actually minerals at all but are instead classified as mineraloids because they do not have a crystal structure. Likewise rocks cannot be described as minerals either because the vast majority are made up of more than one mineral. Many people use the term crystals, rocks and minerals interchangeably but they're actually all quite different.
An example of a rock that's frequently tumbled is lapis lazuli. This blue coloured metamorphic rock is made up of several different minerals so it's neither a crystal or a mineral.
It really doesn't matter whether you refer to tumbled stones as rocks, minerals, crystals or healing crystals. These fascinating and often colourful stones are incredibly tactile and as well as being widely used for their metaphysical properties are also popular with rock and mineral enthusiasts of all ages. Being widely available and generally relatively cheap means that it's possible to build up a collection quite quickly and there's hundreds of different varieties to choose from.
Information about creating your own tumbled stones can be found here.