Strata Gem

October 2002

 

President’s Message

 

Another month is gone and soon our Snowbirds will be flying south for the winter. But now is the time to get ready for our show. Jay and several of the members went to the schools last week. Its fun to go to the schools and talk to the students, they are very attentive and interested in stones. I think everyone should take the opportunity to pass their knowledge on to the younger generation. Then maybe we could get new people involved. I'm writing my message before the show. So in advance I would like to THANK all the members that helped in set up the work and the tear down. Everyone always works so hard to have a great show and I know it will be great.

Remember that the election will be held at the meeting in October. If you have some one in mind please come to the meeting.

 

All life is sacred treat all beings with respect. Enjoy life's journey, but leave no tracks.

 

Donna M. Chavez

President

 

Tooele Gem & Mineral

Tooele Senior Citizens Center

September 10, 2002 7:30 PM.

 

The meeting was called to order by president Donna Chavez everyone was welcomed. The minutes of the last two meetings was read and approved. The treasurer report was read and approved. Jay brought up the fact that the three sign that we use to advertise our show have the wrong address on them Don Smith volunteered to correct the error. Henry Chavez has arranged to have the prisoners help put up and take down the show fixtures, this will be a great help. Jay will need more help doing demonstrations for the school kids this year, there are three more schools this year than last year.

Ardith reported that she had made up three vests a small medium and large for people to try on so they can order the correct size, the vests will be priced at twenty five dollars each, you can pick up the cloth and do it yourself if you want to. Donna has a vendor that can supply us with 5x6 parts bags that we can use for rock bags if it becomes necessary. We will have to pick up the glass showcases, we will need two or three trucks to do it. Mary Jean Feldman is going to have open-heart by-pass surgery in the near future. We need more people to sign up for the kitchen, we have sign up sheets here so sign up tonight.

Dennis has the results for the American federation compaction, Strata-Gem won Honorable mention and the salt casting article won seventh. We still need some one to be President and some one to be Show Chairman next year. We have a new person to be Librarian, I couldn’t hear who it was on the tape. Please post our show flyers, and be sure to get the correct side out. Don Smith won the door prize, David and Pamela Haag will bring the treats for next month.

 

Minutes submitted by

Larry Wilson

Secretary

 

Members News

 

Vise Prez & Editor’s Message:

Due to personal & family health problems, and the meeting so close to the beginning of the month. I won’t be able to put in any show news & welcome new member. I will try better next month.

 

Topaz

By George Judd

 

Topaz has long been used as the November birthstone. The alternate choice for this month, citrine (or topaz-quartz), is much more commonly sold for this purpose. Unfortunately, the name topaz has been applied so indiscriminately to citrine that the beauty of true topaz is all but unknown to most persons. In fact, very little of the so called topaz of the trade is genuine topaz, even in view of a ruling of the Federal Trade Commission that defines as an unfair trade practice the sale of this quartz variety as topaz. Whether it is unethical to sell citrine as the November birthstone has always been a debatable issue. This problem was at least partly solved when, in conformance to the FTC ruling, the American Gem Society adopted a resolution permitting its members to sell both minerals as the November birthstone, providing they are correctly and ethically represented. Fortunately, this practice is gradually becoming more prevalent throughout the entire jewelry trade.

Unlike many of the other gemstones, there are no distinct, well-known variety terms applied to the various colors of topaz, even though it is available in a broad range of colors. Until somewhat recently, most of the varieties were known by incorrect terms that compared topaz with better-known gem varieties and species. For example, such terms as "Brazilian sapphire" and "slaves diamond" were used for topaz that resembled the color of these two gems. Fortunately, these and similar terms have passed into antiquity; they are rarely used today.

 

A. Brownish-Yellow to Yellow-Brown.

The most important variety is that frequently referred to in the trade as sherry topaz. The reason, obviously, is the resemblance of its color to that of sherry wine. The appearance of sherry topaz is often called "velvety"; it has a "softer" quality than that seen in citrine quartz, which is so frequently sold as topaz. A dark-orange to dark orange-red color is sometimes called hyacinth topaz, but it is not a common term or a commonly encountered variety. A slightly orange yellow to yellow or golden-yellow topaz is found in Brazil and is often called Brazilian topaz; however, this name could be applied to any variety of topaz found in that country. It is frequently used with the more or less sherry-colored topaz, as well as the golden yellow.

 

B. Light Blue to Very Light Blue.

Blue topaz has been found in fairly substantial quantities in Brazil. Frequently, it is found in parcels of aquamarine shipped from Brazil to various gem centers. The rough is usually found in comparatively small sizes, but an occasional very large stone reaches the market. One stone of over 3000 carats was cut by a Los Angeles colored-stone dealer, more as a curiosity than as a gemstone. Although blue topaz is generally very light in tone, exceedingly attractive mediumlight stones are sometimes found; of course, they command a significantly higher price. Colorless topaz can, through irradiation plus heat treatment, be turned a deep blue color unknown in natural topaz. This is often sold on the market as a substitute for the much higher-priced dark aquamarine. A very dark blue topaz should have its origin questioned if sold at a very high price, since this color in nature would be a great rarity. Treated blue topaz has become one of the most popular and abundant materials in the gemstone marketplace.

 

C. Pink

Light-red to light-violet-red stones are usually sold as pink topaz. This variety is rarely found in this color in nature, but usually is produced by heating the sherry, brownish-yellow topaz without the use of chemicals. This process is referred to as "Pinking," and stones produced in this manner sometimes are called "pinked" topaz. Although pink topaz is a lovely stone in its deeper tones, it is very rarely seen in a jeweler's stock - it is one of those overlooked beauties among the colored stones.

 

D. Colorless

Another fairly well-known variety is the colorless or so called white topaz. In the past, this stone has been referred to, with a preflx, as a diamond; i.e., "slaves diamond." Its use in jewelry is limited to either inexpensive pieces or to the substitution for diamonds in caliber work or other pieces utilizing small stones. Its value as a gemstone is limited greatly by its comparatively low dispersion and brilliancy; in other words, for topaz to be desirable as a gemstone, it must be valued for the beauty of its color.

 

E. Other Varieties.

Topaz is occasionally found in a number of other colors. Among these are light violet, red of medium tone, and pale greenish yellow to yellowish green. These varieties are either too rare or too little in demand to be encountered frequently by jewelers. If the depth of color of the various varieties of topaz were greater, there is little doubt but that it would be numbered among the most important of the gemstones. It has the durability, a very pleasing appearance otherwise, and it is effective as a ring stone.

Topaz is formed by pneumatolytic processes; i.e., those in which the action of hot gasses plays an important part. Usually, it is found as a constituent of pegmatite dikes, where crystals often attain huge size. It also occurs in cavities in highly acid rocks, such as rhyolite, and in gneisses and schists. Because of its hardness and relativedurability, it is a common constituent in gem gravels.

Topaz is one of the materials formed late in the cooling of a silica-rich igneous mass. The more volatile constituents left and concentrated by the deposition of the materials that crystallize early may act on either the already crystallized materials or on the surrounding country rock. Products of pneumatolytic action, in addition to topaz, include cassiterite (tin oxide), tourmaline and apatite. One of the important constituents of topaz is fluorine, which is partly replaced in some cases by the hydroxyl (OH) ion. Both fluorine and OH are among the volatile materials concentrated by the crystallization of other components of a silica-rich magma. It is probable that the fluorine content of topaz is responsible for its rather low R.I. in relation to its specific gravity. Most fluorine minerals are relatively low in refractive index.

In fashioning topaz it used to be cut in the round brilliant and mixed styles, often with many additional facets. Today, however, step and modern diamond styles are used primarily. Since topaz has an excellent basal cleavage, it must be oriented very carefully, because difficulty in grinding and polishing will be encountered if the table is placed parallel to the cleavage plane. Moreover, if the girdle is positioned parallel to the cleavage plane, numerous small cleavages are apt to occur on the girdle edge. Usually, orienting the table 12 degrees to 15 degrees off the basal cleavage plane or off the length of the crystal will eliminate this difficulty.

When it comes to the value of topaz a lack of knowledge on the part of the public of the existence of the various colors of topaz, other than yellow, has affected the value of gems of great merit and beauty. Its cleavage is sufficiently easy that it is not too wise a choice for a man's ring, unless the style of mounting affords it adequate protection. Most specimens exhibit an exquisite and unusual body appearance. Feathers, flaws (often consisting of liquid or gaseous inclusions), opaque inclusions and poor color are frequent. Clean, fine quality gems are not common. Yellow Russian topaz is subject to fading. Blue stones are unusually beautiful, some rare specimens resembling closely the color of sapphires of the trade grade known as Ceylon sapphire. With rare exceptions, all colors, except yellows and browns, are light to very light (pale) in tone. Other factors being equal, the darker the tone, the more valuable the stone. Pure yellow topaz is encountered infrequently, and even then the value is comparatiely low, since this color may be duplicated by the very inexpensive citrine quartz. The violetish-red stones in fine qualities are the most expensive, followed by pink, sherry and related colors, and then blue and yellow. The more valuable topaz in any color displays a slightly velvety body texture in conjunction with a high, almost sub-adamantine, luster.

 

PHYSICAL AND OPTICAL CHARACTERISTICS

Chemical Composition: A fluosilicate of aluminum

Crystallographic Character: Orthorhombic system. Habit: prismatic, often with pyramidal terminations.

Cleavage: Highly perfect parallel to the base of the crystal.

Fracture: Conchoidal.

Hardness: 8.

Toughness: Poor. Dropping on a hard surface, or even light blows, may damage a stone badly.

Pleochroism: Weak to distinct. Blue: colorless and light blue. Yellow: brownish yellow, yellow and orange-yellow. Brown: yellow-brown and brown. Red and pink: light red and yellowish red to yellow. Green: blue-green and light green.

Luster: vitreous.

Refractive Index: Colorless, blue and green: 1.609-1.617. Yellow, brown and red: 1.629-1.637

Heat: Although topaz is infusible under the jeweler's torch or the blowpipe, it may lose or change color entirely. Too rapid heating or cooling will cause internal cracks or possibly cleavage

Acids: Affected very slightly.

 

From The Rockpile, 10/01

Via The RockCollector 11/01

 

New Fossil Finds

by Gene Thompson

 

A 45 million-year-old fossil of a reptile similar to a crocodile has been found during excavations at Eckfeld in the Eifel region of West Germany. The one-meter-long animal strengthens the belief that the Eifel region once had a “hothouse climate”.

In Mexico, 10 peasant farmers walked into an “enchanted cave” in central Mexico in late May. They planned on digging a water channel from the waters of a natural spring to their village. Instead they found huge bones that scientists say are almost certainly those of at least one mammoth. They have since excavated at least 40 pieces, ranging from huge femur bones to teeth.

 

from Rock Chipper 7/01

via Golden Spike News 8/01

 

Dendritic Mineralogy

 

Dendrites--crystalline, black, fern-like patterns that resemble forest scenes --have captured the fancy of collectors for centuries. Dendrites, normally deposited on fracture surfaces in rocks, are formed from manganese that has been leached from surrounding rocks and soil by water.

For many years, scientists presumed that dendrites were composed of pyrolusite, a manganese oxide common in ore deposits. However, this mineral identification could not be confirmed because dendrites are formed from crystals so small that they cannot be characterized by X-ray diffraction, the standard diagnostic tool for analyzing minerals.

Recently, California Institute of Technology geochemists George R. Romanian and Russell M. Potter applied infrared spectroscopy, an analytical technique that illuminates mineral samples with infrared radiation, to identify the mineralogy of dendrites. Because specific minerals absorb specific patterns of infrared wavelengths, infrared spectroscopy has become a valuable tool for analysis of very fine—grained minerals.

Results of infrared spectroscopy analyses demonstrate that dendrites are formed by any one of several manganese oxides, none of them pyrolusite. Manganese oxides are differentiated on the basis of the internal arrangement of their atoms and the content of some minor elements. For example, the manganese oxide romanechite forms dendrites in pegmatites of the Black Hills region of South Dakota; hollandite dendrites are from Afton Canyon, California; todorokite is found in the gem mines of Pala, California and cryptomelane is from the southwestern United States. Each dendrite is formed from a specific manganese oxide. No mixing of manganese oxides within the dendrite was observed in the samples tested.

Infrared spectroscopy has also been applied to the analysis of desert varnish. It was found that desert varnish is about 70% fine clay and 30% manganese and iron oxides. The manganese mineral in desert varnish is the oxide bimessite. In comparison, dendrites contain virtually no clay, and none of those analyzed thus far has contained bimessite.

 

from Lithosphere 5/93 and 12/98

via The Glacial Drifter 1/02 & others

 

What To Do If You See A Fireball

 

A "fireball" meteor is a rare and significant event, and if you are a witness to one, concentrate on the whole phenomena for as long as it takes. Some things will occur simultaneously (over a short amount of time: light, sound, and changes in direction). Try to take it all in, and use the following ten steps to help you recall the fireball so it can be located by researchers looking for meteorites on the ground.

 

1)   Keep your eye on the ball of light and associated phenomena, and county slowly (1, 2, 3, etc.) until it disappears.

2)   Note time of day.

3)   Listen carefully for any sounds at the same time as the light and up to two or three minutes later.

4)   Notice landmarks, buildings, poles, fences, trees, etc., below where you first saw the fireball and where you last saw the fireball.

5)   Notice the height above the horizon where you first see it and last see it. (You can use landmarks for this too.)

6)   Pay attention to the end: Did it fade out, blink out, fragment, explode - and - what about pieces falling off? Try to keep a mental/visual image of the event (was it shadowed, color, light intensity, flickering and end).

7)   Watch for a smoke or dust trail after the fireball: Was there a smoke trail after falling pieces...after the fireball?

8)   If you are under the fireball listen for falling objects, even small marble or hail like pieces, or where larger pieces may have hit and could be buried in the ground.

 

After the event ends:

9)   Memorize your exact location so you can return with a field researcher. (Write down notes and a sketch of what you saw with landmarks noted.)

10) If you have a compass, take a bearing and plot your location on a map. Directions of first and last sightings and the first and last angles above the horizon are very important. For field researchers, this is the best way to locate the flight path and end position of the fireball; therefore any compass bearings you take become very important information.

 

If you think it is a significant event, you may want to report it on the internet at www. dmnh.org. This will allow researchers to use your position and observations to triangulate and locate the longitude and latitude of where the fireball breaks up in the sky and ultimately, to describe a potential impact area on the ground where meteorites might be found.

 

To report a “Fireball” sighting: Write down as much information to the above questions as possible and mail to:

Denver Museum of Natural History

Department of Geology

2001 Colorado Blvd

Denver CO 80205

 Or call and leave your name and telephone number: 303.370.6445 or 303.370.6473.

 

(The foregoing article appeared in “The Gates Rockhound Bulletin, Volume 32, June-July-August, 2002. No author was given and the in formation given is for the Denver/Colorado area. Contact the local Geology Department of museums in your area to find where to report in formation outside the State of Colorado.)

 

via RMFMS Newsletter 8/00

Food For Thought:

Living on earth is expensive, but it does include a free trip around the sun.

I have enough money to last me for the rest of my life-unless I buy something.

Via Golden Spike News 7/02

 

The Absent Minded Rockhound

 

A certain rock hound was exploring the geode country of Oregon. One day he came upon an unusual geode. To see it better he spit on it and rubbed it on his sleeve. Suddenly, a genie appeared and said, “I am the Genie of the Geode. Because you are a good rockhound, I will grant you three wishes.”

After thinking a bit the rockhound said, “I’ve always dreamed of owning a collection of diamonds. That’s my first wish.”

Poof .a fabulous collection of diamonds appeared. The rockhound thought of his pickup rig which was in bad shape and wished for a new one with all the trimmings.

Poof - - a brand new rig with all the trimmings sat before him. The rockhound then asked the Genie if he could save his last wish for later. Because he wanted to think about it for a while. The Genie nodded and disappeared.

The rockhound placed his diamond collection in his new rig and headed for home, happy as a lark. He turned on the radio and began to hum. Soon he was absentmindedly singing along with the music... ‘Oh, I wish I were an Oscar Meyer Weiner... “Poof..

 

Via Northside Gem & Hobby News et al.

Via Rock Chip Reporter 3/02

Via Hy Grader 2/02

 

Kids Corner

A Quiz For You

by Kim Cochran

What geologic era do we live in?

a.) Cenozoic            c.) Paleozoic
b.) Mesozoic            d.) Now

 

If’ you said Mesozoic (b), you are completely wrong. We live in the Cenozoic Era. Man has always been preoccupied with time. It is a measure of’ what we do today, what we did in the past and what we plan to do in the future. When man realized that earth history extended so far back in the past, it became necessary to assign periods of time to those ages. In this way, man could have an understanding of what lived and what took place when. Time has been divided into Eons, then Eras, Periods and Epochs

There have been two Eons: the Cryptozoic, what we know as the Pre­cambrian and the Phanerozoic. The Cryptozoic covers most of’ earth’s history. During the majority of’ this time there was no life on earth. Later very primitive life developed. At about 6oo million years ago, there seems to have been an “explosion” of life. Actually, there was probably abundant life in the latter portion of the Cryptozoic, but for some reason evidence of’ this life was not preserved.

At the beginning of the Phanerozoic Era, there were examples of every plan of life forms which exist today, from protozoan, to arthropods, to very primitive chordates (the phylum to which man belongs). The Phanerozoic Eon is divided into the Eras: the Paleozoic, Masozoic and Cenozoic in which we live. The Cenozoic (dependent upon which author you read) is divided into two periods, the Tertiary and the Quaternary, the latter of which we live in today. The Quaternary Period is further divided into two Epochs, the Pleistocene (in which the last Ice ages occurred) and the Holocene (or Recent) Epoch. The Holocene Epoch began only 10 to 12 thousand years ago.

Each period of’ time is distinguished by its own distinct and dominant life forms and/or major geological event. At the end of most of the time periods, there was usually a great extinction event in which most of’ or all of whole groups of animal and/or plant life were wiped out. At the end of the Pleistocene most of the great ice age animals (e.g. mastodons, wooly mammoths, giant bisons, etc.) became extinct, leaving the life forms that we are familiar with today.

 

from GEM CUTTERS NEWS 11/99

Via The Glacial Drifter 1/02

 

The Story Of Cameo Carving

by Russell H. Hensen

 

Humans carved stone at least 50,000 years ago to produce recognizable forms of the human figure and animals, In the Aurignacian period of Stone Age culture, 40,000 to 15,000 BC, many pieces of remarkably credible carvings in stone were produced. The most famous of these is the Venus of willendorf, a fertility statue from willendorf, Austria.

The peak of stone carving, as we recognize it today as lapidary art, occurred in Nesopotamia, where the Sumerian and Hittite carvers did work of consummate skill. Their main product was incised cylindrical seals, made of available gemstones: lapis, carnelian, aventurine, malachite, and others.

Apart from their ornamental and eye appeal, these seal—stones or signets were objects of real value. They were carved in intaglio, so that the impression made from it was in bas-relief. The clay impressions made by this seal insured documents and property against tampering or intrusion as any breakage was clearly visible. Thousands of seals were made and the carving business continued until at least 400 BC.

 

Egyptian Carving and Scarabs

Influenced no doubt by the Mesopotamians, the Egyptian stone carvers became highly skilled and their most common product was the scarab, its religious significance connecting it to the dead. In distribution, the scarab carvings spread this lapidary art to Greece and Italy. By the fourth century BC, the style and design of gem carvings had become entirely Greek—influenced, and the emphasis changed from incises, or intaglio, to bas relief, or cameo. Thus cameo cutting returned to Egypt and the city of Alexandria became the center of this art form for many years.

 

What is Cameo Cutting?

Cameo cutting is the lapidary art of relief carving on material that has two or more straight parallel layers of contrasting color. Those materials with a darker lower layer that could be used as a background were preferred; the lighter, upper layers became the image.

This art eventually settled in Italy and in Rome. Here it flourished during the first century BC and AD. With the decline of the Roman Empire, cameo cutting de­teriorated in most of Europe, yet it was kept alive in Spain by the Moors who brought their craftsmen from the East.

Eventually, the political and religious pressures led the practitioners of the lapidary art to emigrate to France and the Netherlands, where their product received much acclaim. In Paris, at the end of the thirteenth century, a guild of lapidaries was formed and this was followed by a similar guild in Nurenberg. Johann Gutenberg of this town, famed for his movable type and Bible, was a highly skilled gem and cameo cutter.

 

Materials Used

The cameos were also carved in transparent and semi-transparent gemstones such as crystal, citrine, topaz, amber, chalcedony, agate, and carnelian, and in opaque materials like mother-of-pearl, ivory, lapis, opal, or turquoise. However, because of the difficulty in obtaining suitable pieces of hard gemstone to carve, the abundant, available, and easy to carve shell material became the item most carvers used. For every hundred cut in gemstone, thousands were cut in shell.

 

Common Material

The helmet shells used in cameo cutting belong to the molluscan family Cassidae, with a worldwide tropical and temperate seas distribution, For the larger pieces, Cassis madagascariensis (once called Cassis cameo for its use in this art form) was used. Cassis tuberosa, with its darker inner layer, was preferred for the smaller carvings. Both of the above shells were obtained from the trade in the Florida-West Indies area. Cassis rufa from East Africa furnished material with a dark sardonyx background and lighter orange-red image. Broken pieces of the helmet shells were utilized in the making of pendants, brooches, clasps, and rings.

The chambered nautilus shell was used extensively by the cameo carvers in making elaborately carved and mounted drinking vessels. Other seashells were tried, such as the pearl oyster, tiger cowry, turban shell, pink conch, and many more, but none have reached the popularity of the helmet shells in this lapidary art.

 

from the Mountain Gem 9/95,

via LAKE AGASSIZ ROCK HOUND 2/01

via The Glacial Drifter Feb./Mar. 2002 & others

 

New Method of Tumbling

by Al Nutile in Tulip City Conglomerate

 

The writer believes that the following idea can take much of the work from the popular method of tumbling. All of the instructions we have seen state: “Wash stones and tumble very clean between each change of grit or final materials,” at the same time stating, “If liquid is too thick add some slurp or grit from previously used material.”

We know some will argue against our method, but here goes: Don’t wash at all after each week of tumbling with grit! Start with #50 grit, tumbling a week. Then DON’T EMPTY THE TUMBLER, but add 5 tea­spoons of new grit [one step finer] to the mixture in the three pound tumbler. Follow this procedure through #190, #320 and #600 grit. Now [finally] thoroughly wash the stones and tumbler before pre-polish and final polishing.

For a really glossy finish, take one or more weeks [after washing out the polishing powder] adding three spoons of sugar, one spoon [level] of Cascade or All or any non-sudsing detergent and add about ten drops of muriatic acid, if you have some, let stand one minute - open, close tub, and tumble for a week.

We have run eleven tubs using this method and found that even ordinary sandstone comes out highly glossed. Except for extra final steps, you save three washings and getting rid of the slurp each time. Saves time, work and mess, and still gets a better polish.

 

From Pickin's & Diggitis 7/96

via Rock Chips 6/00 & others