Thursday, July 16, 2009

Identify Tumbled Stones







Smoothly polished stones are often used in jewelry.


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.


Instructions


1. Although quartz naturally forms crystals, tumbled pieces have no points


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.


2. Turquoise stones are often shot through with veins of other colors.








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.


3. Many stones feature bands of color when sliced and polished.


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.

Tags: stones often, tumbled stones, rock tumbler, your stone, bands color, common stones, jasper agate