The term "tumbled stones" refers to stones that have been put through a rock tumbler. A rock tumbler uses grit and/or vibration as a medium to turn rough-edged or raw stones into stones with rounded edges and a soft shine. These stones are often more than ordinary rocks, many of them gemstones specifically selected for this type of polishing. These stones can be used in jewelry, gemstone therapy or set out as decoration. A wide variety of stones can be put through a rock tumbler and so identification of specific rocks is often a challenge. A set of tumbled stones is often a mix of common stones including jasper, agate and quartz.
Things You'll Need
- Magnifying glass or loupe
- Light source
- Gemology guide
Hold your stone up to the light. Is it translucent? Does the light shine through the stone either partially or completely? Stones that are clear and look a bit like melting ice are generally clear quartz. Other types of quartz are also pale or translucent including citrine (golden yellow) and amethyst (purple), as well as pale pink rose quartz. Just because a stone is translucent does not mean that it is a quartz, other stones such as tumbled aquamarine, which is of the beryl family, exhibits similar characteristics. There are stones that the light does not shine though. Most stones in a tumbled group are actually are at least partially opaque and many are fully opaque. These include jaspers, agates, onyx, bloodstone, lapis and malachite among a wide variety of minerals.
Evaluate the color of your stone. Color can help determine what kind of stone you have, but there are hundreds of types of stones. A deep denim blue with white splotches may be sodalite ,a commonly occurring stone, while a lighter blue can be turquoise, chalcedony or blue apatite. A pink stone can be rhodocrosite or rhodonite. Does it have a metallic appearance? Those stones are often iron-rich hematite or pyrite, the mineral aptly known as fool's gold, while a stone that displays a iridescent shimmer may be labradorite. Some stones naturally have bright colors but many stones, especially agates, can be dyed and take on an overly saturated shade.
Examine the stone's other characteristics. Deep bands of color can indicate tiger's eye if the stone is brown or red, but banded agate is more common. Spotted stones can be one of many types of jasper or agate. A black stone with white splotches is often snowflake obsidian. A pattern that resembles wood grain could mean that the stone is actually petrified wood. The color of the stone's inclusions can lend a clue. Goldstone is a man-made stone featuring bright copper flecks. Much identification can be done by visual inspection, comparing your stone to images of other common stones either at websites selling tumbled stones or by using a mineral field guide (see Resources). Crystal stores often sell tumbled stones, many grouped by category, which can help make identification easier.
Tips & Warnings
- Local rock clubs are great places to learn more about stones. Some rock clubs also have access to shops where you can learn to cut and polish your own stones.
- Photo Credit Jupiterimages/Photos.com/Getty Images Hemera Technologies/AbleStock.com/Getty Images Hemera Technologies/PhotoObjects.net/Getty Images
- Rainbow Crystals: Gemstone Guide
- Rock Tumbler: Polished Stones List
- A Field Guide To Rocks and Minerals, Frederick H. Pough, 1998
- Gemstones (Smithsonian Handbooks), Cally Hall, 2002
- Gemstones of the World: Newly Revised & Expanded Fourth Edition, Walter Schumann, 2009
- Geology.com: Tumble Polished Stones
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