Agate tumbling rocks are the most popular. Agate is generally inexpensive and can be tumbled with good results by beginners. It has a hardness of 7. Agates form under sedimentary conditions. They consist of alternating layers of fibrous chalcedony (cryptocrystalline quartz) with circular to semi-circular layers, patterns, or bands like rings of targets. These layers may be composed of different thicknesses and colors. The rainbow of colors are caused by impurities and occur as alternating bands within the agate, creating interesting and pretty patterns. Agate tumbling rocks can have many names, which are based on appearance or location. Amethyst is a purple variety of crystalline quartz with a hardness of 7. Once a precious stone, the discovery of large deposits in Brazil has reduced its value to semiprecious, although the finest grades are still faceted and set with diamonds. The principal virtue of amethyst during the Middles Ages was to protect the wearer against drunkenness from either liquor or love, and to induce clear thinking. Aventurine is a variety of translucent quartz with abundant small flakes of mica, ilmenite or hematite that reflect light and produce a sparkly appearance. The name aventurine comes from the Italian "a ventura," which means "by chance" which is how the sparkly flakes were first discovered by Italian glass blowers. This rock is known as a lucky talisman and, therefore, is a popular stone for gamblers. Aventurine is a very good tumbling rough. It polishes easily and is usually inexpensive. Its hardness is very close to that of quartz, agate and jasper, so all of these can safely be tumbled together. Many believe that aventurine has the capacity to calm a troubled spirit and bring about inner peace. Bloodstone is a form of dark-green microcrystalline quartz with red inclusions. Hardness of 7. An easy stone to tumble polish, bloodstone was once, like amethyst, more precious than it is today. The larger the flecks of "blood" the better the grade. The stone was thought to stop bleeding when pressed against a wound and to neutralize poison. Carnelian is a popular semiprecious gemstone that occurs from translucent orange to red to brown, and is one of the most frequently tumbled agates because it easily tumbles to a high polish. Its Mohs Hardness is a 7, so it tumbles well with similar hardness stones such as agates, jaspers, and quartz. Folklore suggests this gem was used protect the traveler after death and guard against evil. Carnelian's healing properties are thought to help purify the blood, relieve menstrual cramps and back pain. It is also thought to be beneficial in the treatment of infertility and is worn to enhance passion and desire. Chalcedony has a hardness of 7 and is a microscopically crystallized variety of quartz (silicon dioxide) in which the crystals are arranged in parallel bands of slender fibers. The variety must often tumbled ranges in color from milky to sky blue. The stone is supposed to drive away ghosts or phantoms to prevent nightmares! Garnet is not always red. It can also be green, yellow, brown, translucent or opaque with a hardness of 6.5 or 7. The most often tumbled is translucent red (almandine). Like many red stones, garnets were once thought to convey immunity to wounds. By reversing the logic, the Hanzas, when fighting the British in northern India in the 1890s, used garnets as bullets in the belief that they would inflict incurable wounds. Gypsum is hydrated calcium sulfate with a hardness of 2.5. The gem varieties are alabaster and yellowish satin spar. Gypsum is thought to bring general good luck to its beholder. Hematite varies in hardness from 1 to 6.5. Only the harder varieties may be tumble polished or cut. Sacred to the god of war, hematite was long ago believed to confer invulnerability. American Indians used the softer varieties of the stone as war paint and the hard stone in jewelry and amulets. The hard stone appears dead black or silvery but if rubbed across a rough white surface will leave a red streak. Jade is the Chinese good luck stone and is very valuable. It has a hardness of 7. Jasper occurs in a variety of colors and has a hardness of 7. The green type was thought to be valuable for bringing rain while other types were thought to occur in the head of a certain type of adder and hence were used to draw out venom. Like bloodstone, jasper was also thought to stop bleeding. A few names for jasper include cycad, regalite, and tempskya. Lapis Lazuli is generally an expensive rock to tumble, but because of its beauty, this bright blue gemstone that has been popular since ancient times. The Egyptians used it for seals, ground it for an eyeshadow, and often carved it into vases and figurines. It is said that the Romans used lapis as an aphrodisiac. In addition to lazurite, this rock also contains calcite (white), sodalite (blue) and pyrite or fools gold (metallic yellow). It has a hardness of between 5 and 6, so is best tumbled alone and recommended for experienced lapidaries. Moostone reflects a bluish sheen from certain crystal directions; this characteristic is known as adularescence. A potassium aluminum silicate, it has a hardness of 6. Folklore says moonstone is supposed to arouse love. To determine the future of a love affair, the stone should be placed in the mouth during a full moon. But it is unknown what should happen to indicate good or bad tidings. Obsidian or Apache Tears is a naturally occurring volcanic glass that formed from quickly cooling lava. Often called the stone of truth, the black obsidian can reveal boundless secrets and mysteries, and looks beautiful when polished. This rock is 5.5 on the Mohs Hardness Scale, so is best tumbled separately. Instead of allowing them to tumble a week in coarse grit, check them after four to five days. Since silicon carbide has a hardness of 9+, the piece will wear away rapidly, and you don't want to open the tumbler and discover that your rocks are the size of peas! Opal with lots of "fire" is usually too valuable for tumbler polishing, but thee colorless variety, hyalite, and fire opal (orange red and translucent) are often tumble polished. The opal was once thought to be the premier good luck stone. Opal cracks very easily. Hardness of 5 to 6. Rhodonite is typically pinkish in color and has been used indoors as an architectural stone, and is often used to produce beads and carvings. This manganese silicate mineral is frequently tumbled and is a good rough material for experience tumblers. The material most often offered as a tumbling rough is inexpensive material with significant amounts of black manganese oxide. It has a hardness of between 5.5 and 6.5 and is best tumbled with materials that are softer than quartz, agates and jaspers. It can be challenging to polish because the manganese oxide can have a different hardness than the rhodonite. Rose Quartz is known as the love stone and is a good tumbling rough for beginners. It is usually a solid material that accepts a very high polish. It has a hardness of 7 and tumbles well with other quartz materials, agates and jaspers. Its pink color and high polish make it a very desirable material, and luckily it is usually inexpensive. It is said that washing your face in water charged by rose quartz will help fade wrinkles and keep the skin young. Ruby is a red form of corundum (aluminum oxide) colored by chromium oxide with a hardness of 9. This precious stone is believed to convey all sorts of virtues such as remove evil thoughts, preserve health, control desire, reconcile disputes, and more. Folklore says to convey these things, wear the stone in jewelry on the left side of your body. Ruby was one of the first precious stones to be made synthetically in the 1890s. Inferior stones are often tumbled. Sapphire is blue corundum with a hardness of 9. The best varieties are a very deep translucent blue. A "star" sapphire is more opaque and contains microscopic inclusions that produce the star effect. The star variety is said to bring good luck and to ward off the evil eye! Tiger's Eye is a member of the quartz group. Many legends say wearing it is beneficial for health and spiritual well being. Legend also says it is a psychic protector, great for business, and an aid to achieving clarity. Whether you want it for those reasons or just because of its silky luster when light is reflected within the thin parallel fibrous bands, Tiger Iron is one of the chatoyant gemstones containing red jasper and black hematite. Topaz has a hardness of 8 and is aluminum fluorosilicate. Don't confuse this with the smoky quartz often sold in gift shops as "smoky topaz." True topaz comes in a variety of colors from blue green to yellowish brown. Turquoise is hydrated basic aluminum phosphate with copper. Ranges in color from sky blue with brown veins, to brilliant blue-green. This stone, hardness 5-6, has always been sacred to Indian tribes in the western USA. |
