Many small rocks, gems, minerals and pebbles are suitable for polishing — by hand or for more efficiency, with a rock tumbler. Through polishing, some rocks will simply be shiny while others will reveal beautiful layered bands or imperfections that give them unique character. Colors will brighten and rough edges will become smooth. Avoid polishing rocks with fractures, cracks or large protrusions as they can harm the equipment as well as damage other stones. Sometimes it can take days for a tumbler to complete the task.
Agates and Carnelian
Agates are a good choice for polishing. They come in a variety of colors and are easy to identify. If you comb beaches for agates and carnelian, they're easiest to find when the sun's slope is low as it back lights the rocks. Agates and carnelian stand out when lit from behind, glowing like raw jewels. Carnelian is typically an orange or reddish-orange color. Sometimes you will see bands inside or across the rocks. Blue agates, agatized coral, moss agate, brown agate, lace agate and other types can be polished.
Clear quartz, rose quartz, smoky quartz and blue quartz can all be polished, provided there are no voids or protrusions. All members of the quartz family can be considered, including chalcedony, amethyst, and rutilated quartz — which has golden or reddish strands of rutile inside. The beautiful orange-golds of citrine polish up well, too. Aventurine is usually green, but you can also find it in yellow, blue, orange, gray and brown. If you are uncertain about the type of rock, ask at the mine, quarry or rock shop. The people who run them will also be able to indicate whether or not a particular stone is good for polishing.
Jaspers and Tiger's Eye
Jasper is about as common as agate and is opaque. It is a member of the quartz family, however isn't at all clear. It usually features stripes or lines and some jasper rocks are called "picture rocks" because the features look like desert landscapes or figures. The rocks are usually red, but occur in yellows, browns and green. Tiger's eye is another form of quartz, but like jasper is not clear or see-through. It is usually yellow or brown, but can sometimes be found in blue. The yellows combined with the striped qualities in most tiger's eye lend to the name.
Feldspars and Malachite
Malachite is a crystalline form of copper that gives it the rich green color. Often banded, it is a beautiful rock for polishing. Among the stones that fall into the feldspar group are labradorite — which is bluish and often highly iridescent. Moonstone, sunstone and spectrolite are examples of the iridescent types. Microcline and amazonite are blue-green and translucent, but can come in other colors. Some of the feldspars look like granite or dull rocks, but upon further investigation have qualities that appeal to many collectors. Orthoclase and albite are also among the many other feldspars.