Lapidary Polishing Compounds (Golden Spike News, 4/01)
For economy dedicate a buff, lap pan to a particular polish and simply recharge with fresh polish as required to maintain effectiveness.
Cerium Oxide - the best gemstone polishing compound for most uses. Best with opal, agate, quartz, obsidian. Not as effective with soft material or stones that tend to undercut. Micron Alumina - a 5 micron polishing powder developed for computer disks. It is the best polish for seashells, pretty good for soft stones and excellent as a pre-polish in vibratory tumblers and laps - not rotary tumblers.
Aluminum Oxide, MAP - preferred by many to Linde A, this is a slightly faster and more economical rare earth polish that we call Miracle Atomic Polish.
Tin Oxide - a long time favorite. Use on leather for polishing turquoise and all soft stones.
Zirconium Oxide - a rare earth polish that is especially good for tumblers and laps. The most economical effective polishing media. White and will not discolor gemstones.
Linde "A" - A tremendous favorite with gem cutters whether faceting or polishing cabs. Relatively expensive, you should consider polishing the stone then giving it a quick hit with Linde A to attain a super polish. Available as powder to mix with water or an emulsified cream with the consistency of hand lotion that does not separate in solution
Oxalic Acid - used for polishing carbonate type onyx when mixed with another polish such as Tin Oxide. In a strong solution with water, it is used to clean iron stains from specimens, i.e. Quartz. Mix with hot tap water by stirring in oxalic crystals until the water is saturated and will not dissolve any more. Crystals forming along the sides of the container indicate a saturated solution and should they disappear, you need to add more. WARNING: While this is a relatively mild acid all precautions must be taken to keep it out of eye, mouth, etc.
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Whoa! Don't Buy That Shiny Gem (via Flint Flashes 12/09, via Golden Spike News-5/01, Chips-12/00, Rock Rollers-11/00
Technology has given new meaning to the old phrase "hot gem". As you know irradiation can darken a crystal producing a deeper color. Deep, vibrant colored gems also sell for top dollar. Now what's supposed to happen is the gem is radiated then stored in a lead container for several years until the radiation has dropped to safe levels. More time means more overhead. Unfortunately, some traders care more about reduced overhead than morals and have released HOT cat's-eye gems to the market. Some of these were measured at 51 times the US radiation limit. Buyer Beware! If you're not careful, more than your watch will glow in the dark.
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ALEXANDRITE
This rare gemstone is named after the Russian tsar Alexander II (1818-1881), the very first crystals having been discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. The discovery was made on the day the future tsar came of age. Although alexandrite is a relatively young gemstone, it certainly has a noble history. Since it shows both red and green, the principal colors of old Imperial Russia, it inevitably became the national stone of tsarist Russia.
Beautiful alexandrite in top quality, however, is very rare indeed and hardly ever used in modern jewelry. In antique Russian jewelry you may come across it with a little luck, since Russian master jewelers loved this stone. Tiffany's master gemologist George Frederick Kunz (1856- 1932) was also fascinated by alexandrite, and the jeweler's firm produced some beautiful series of rings and platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller alexandrites were occasionally also used in Victorian jewelry from England.
The most sensational feature about this stone, however, is its surprising ability to change its color. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities.
Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colorless or yellow transparent chrysoberyl, chrysoberyl cat's eye and color-changing alexandrite (also in cat's eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a major impurity. And it is this very element which accounts for the spectacular color change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of color may be termed alexandrite.
Like many other gemstones, alexandrite emerged millions of years ago in a metamorphic environment. But unlike many others, its formation required specific geological conditions. The chemical elements beryllium (a major constituent in chrysoberyl) and chromium (the coloring agent in alexandrite) have contrasting chemical characteristics and do not as a rule occur together, usually being found in contrasting rock types. Not only has Nature brought these contrasting rock types into contact with each other, but a lack of the chemical element silica (the second most common element in the Earth's crust) is also required to prevent the growth of emerald. This geological scenario has occurred only rarely in the Earth's history and, as a result, alexandrite crystals are very scarce indeed.
Article from http://www.gemstone.org/gem-by-gem/english/alex.html
Photos from http://www.gemsociety.org/info/gems/Alexandrite.htm, http://www.khazargems.com/
<http://www.mysticgames.com/gems/Alexandrite.htm>,
From Quarry Quips January 2010
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Tips & Tidbits
From The Rockcollector 12/2009
More Comfortable Cab Cutting-Is the edge of your cab machine water trough sharp? When you're cutting a cab, does the edge dig into your wrist or arm? Here's an easy and inexpensive solution to end your discomfort. Get a piece of foam pipe insulation from the hardware store and place a piece of it over the edge of the trough. Voila, no more discomfort! And, you can easily remove the foam when you go to
empty or clean the trough (from Gem Cutters News 6/08 via The Rockhounder 11/09).
Working with Dark Colored Moss Agate-like the black Montana variety, small pits may sometimes appear on the finished, polished surface. The light colored polishing powders, such as tin oxide or cerium oxide, often pack into these small pits, making removal difficult and white spots surely distract from the
stone's appearance. Try rubbing a small bit of black India ink into the spotted area, and then try to rub off the ink. The white spots will disappear (from Rockhound Rambling 9/08 via Quarry Quips 8/09).
Need a Compass?-If the sun is shining and you have a watch with an hour hand, you have a compass. Set the watch face up and arrange a slender object, a match or a flower stem, upright at the rim of the
watch in such a way that it's shadow lays atop the hour hand. No matter what time it is, halfway back from the hour hand to the number 12 is south (from Petrograph 4/04 via Shawnee Slate 9/09).
Keeping Ivory in Light-Don't put ivory in the dark! It is one substance that needs light. If it has started to yellow, take half a lemon and rub it in some salt. Then rub it over the ivory object. The lemon will work on the yellow discoloration. After it is dry, dampen a soft cloth with lukewarm water, and rub the ivory
All via 12/09 Pick & Pack
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Any Questions Call or E-mail: Judy Budnik at 513 575-1990, wisoh@msn.com or
Charles Rudokas at 513 932-0591, cprfacet@aol.com
