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The Theo Chronicles


Theo Steinhauer

Agates and Jaspers...Best Choice for Beginners

For cutting cabs, my favorite kinds of rough are certain colorful agates and jaspers that are hard and easy to polish and generally have few fractures, pockets and other imperfections. The agates that generally fit these specifications are Brazilian agate, Montana agate and many kinds of dendritic agate from US locations. The jaspers that I like and seem to me take the best finishes are Bruneau jasper, Biggs jasper, Owyee jasper, many similar jaspers from US locations, the Imperial jaspers from Mexico, and bloodstone and fancy colored jaspers from India.

Moss and plume agates, many sagenite agates and jaspers and agates that merge into quartz formations are only second choices when choosing easy-to-cut rough. All of these stones require the touch of the experienced lapidary to deal with all the vugs, fractures, varying hardness and other problems likely to arise during the shaping and polishing of these stones.

Trumming

Trumming is an ancient method for sanding and polishing delicate or intricate areas too small for hand or machine working. A small nylon cord is held in a vise. The other end is held in the hand, pulled tight and rubbed with abrasive or polish compound. The cord is then pulled through the opening in the design, pulled tight. Polishing and sanding is done by moving the work back and forth with pressure. Using tripoli on the cord does a fine job on sawed designs in silver or gold.

How Big is a Carat?

Cut precious stones are sold by the carat, along with the rough they are fashioned from and a carat is standardized as one-fifth of a gram and the carat is subdivided into a hundred parts called points.

The carat weights of some common objects are as follows: a common paper clip weighs 2.9 carats, abbreviated ct, a regular metal staple, 17 points, abbreviated pts, a dime, 11.25 ct, and a one cent, 15.55 ct. A brilliant cut one-carat diamond measures about 6.5 millimeters, mm, across the girdle.

Changing Color in Stones by Heating

Heat treatments of lapidary and jewelry rough stones have been practiced in the east for centuries. In Europe heat treating has been used for at least 200 years. Careful heating by gradually raising the temperature to the neighborhood of 600 degrees F and then cooling back to normal temperature alters the colors of some stones by changing the chemical structure of the coloring material. Both rough and cut stones are sometimes subject to this process.

Generally the stone becomes paler in color or it assumes a more attractive color. In several stones the color becomes darker. Some aquamarines lose their greenish cast and become darker in the process.

Many topazes are naturally an unattractive brown and heating often causes them to turn pink--all pink topazes have been heat treated. Zircons also and are all blue, colorless and golden-brown stones can be assumed to have been given this cosmetic lift. Amethyst becomes citrine by this method.

Heat Stick

Beryllium is a rare metal which has the property of absorbing immense amounts of heat, hence the name heat stick. A spoon made of beryllium, if placed in a cup of coffee would immediately absorb all the heat, leaving a cold cup of coffee. It is used in the nose cones of rockets, making the exploration of space possible and new uses are being found for it every day in industry.

Petoskey Stone

Petoskey stone is a fossilized Devonian coral found only in Petoskey Michigan. Its origin has been traced back to the Devonian seas which covered Michigan's lower peninsula nearly 350 million years ago. The skeleton of this material was preserved and the original material was replaced by silicates in a process of petrification.

Adularia

Adularia is the name sometimes given to the finer grades of moonstone, of the translucent colorless to milky gem variety of orthoclase. This grade is primarily from Ceylon. When properly oriented and cut as a cabochon, it has an optical phenomenon of a floating billowy line of light that travels across the cab in a certain direction as the stone is turned. This peculiar effect is called adularesence. It is caused by diffuse light reflections from parallel intergrowths, in albite feldspar, which has a slightly different refractive index than the main mass of orthoclase.

What is Charity?

It is silence--when your words would hurt.

It is patience--when your neighbor is curt.

It is deafness--when a scandal flows.

It is thoughtfulness--for other's woes.

It is promptness--when duty calls.

It is courage--when misfortune falls.

Aragonite

In 1796 it was announced that a new mineral had been discovered at Molina de Aragon, in the Pyrenees of Spain. It was common practice, as it is today, to name the mineral after the locality where is was discovered, so the twinned pseudohexagonal crystals were called aragonite.

Aragonite and calcite are polymorphs of the same mineral, calcium carbonate. It is remarkable that these two minerals are not far behind quartz in abundance and variation of form, with calcite itself appearing in several hundred different crystal forms.

Glyptography

Glyptography is the art of stone engraving and the carving of small objects of art, including the cutting of cameos, intaglios and the cutting of seals. The oldest examples of this art is probably the cutting of seals by ancient Sumerians, Babylonians and Assyrians. The scarabs of Egyptians follow as a close second. Perhaps the Japanese netsuke is about the best example of the practice of glyptography in modern times.

Chiastolite

Chiastolite is sometimes referred to as a macle and it is an opaque variety of andalusite, containing black carbonaceous inclusions. These inclusions generally have a definite arrangement, laying in two perpendicular planes, so that when cut crosswise, they present a figure somewhat resembling a cross.

Angstrom Units

Lightwaves, radio waves and the rest of the electromagnetic spectrum are measured in Angstrom units, sometime abbreviated A.U. which is simply a very small unit of length. An inch contains 254,001,000 A.U. The following table shows the relations between the inch and several metric units, including the Angstrom unit:

1 meter=39.137 inches
1 millimeter=0.03937 inches
1 micron=0.00003937 inches
1 A.U.=0.000000003937 inches

Color of Minerals

Color is a spectacular and variable property of minerals. Some minerals always have the same color and their name often denotes the color. Azurite is derived from the Persian word for "blue," Lazulite from the Arabic word for "heaven" and Pyrope from the Greek word for "fiery-eyed." In other cases color is not at all an intrinsic property of the mineral. Beryl, celestite and fluorite all occur in a variety of colors. Color centers, or F centers, are a common cause of colors, especially in the group called "alkali halides." Electrons occupy the sites which normally would have been occupied by anions (negative ions). These electrons are described as F centers and their absorption of visible radiation causes the coloration of the mineral. Free electrons may be produced by radiation, and on long exposure to natural radiation calcite, fluorite, halite and other minerals show coloration produced in this way.

Gypsum in its Various Disguises

Often found in massive beds in sedimentary rocks, or as free crystals in clay beds, or in limestone cavities as crystals, gypsum is common and sometimes looked down on by mineral collectors. Fishtail twins, single crystals up to three feet long (sometimes with a moving bubble enclosed within the crystal), satin spar, selenite crystals, alabaster rough, clusters of blades of gypsum crystals etc. are all available to mineral collectors.

Gypsum is that soft stuff that can be scratched with a fingernail, glassy luster, hardness only 2+, gravity 2.3, with a fluorescence in yellow, often showing an hourglass pattern within the crystal. It is colorless, or of light tints, sometimes banded or sometimes evenly colored. Plaster of Paris is made from it because it is only calcium sulfate loosely combined with water. The gypsum is heated and part of the water of crystallization is driven off. When water is again added the plaster of Paris is changed back to gypsum. This very widespread mineral is a fine species to collect because of the great variety of inexpensive specimens available.

Ownership of Meteorites

Meteorites are scarce, very few are found. But once a meteorite is found, the question of ownership comes up. If the object is recovered on land belonging to an individual, ownership belongs to the holder of the deed to the land, and not the finder. In the case of the great Williamette meteorite litigation over the ownership was finally settled by the Oregon State Supreme Court who rendered their decision in these words: (Lange 1962) "Meteorites embedded in the earth are real estate and consequently belong to the owner of the land in which they are found."

On the other hand if a meteorite is found on land owned or controlled by the United States government, under the Act of Congress, June 8, 1906, it may not be removed unless allowed by the US government through the Smithsonian Institution, whose permission must be obtained before a meteorite may be moved if lying on federally controlled land (Linsley 1939). Reference: Mineral Information Service, July 1966, "The Meteorites of California" C.P. Butler.

Soluble Minerals

Many minerals such as sodium chloride (salt), a number of soluble copper minerals and soluble nitrates are easily dissolved. These minerals occur mostly in the world's most arid deserts. They are formed when lakes disappear or where underground waters carry the dissolved minerals to the surface as the water gradually seeps upward to the topsoil. The great Atacoma desert of Chile is one extremely arid area, stretching along the border between Chile and Peru for about 600 miles. In this desert, the average annual rainfall is only one thirty-second of an inch.

Habent Sua Fata Libelli (Books have their fate)

Not a single original manuscript has survived from the writings of the classical Roman and Greek authors. True, many copies of these writings have survived, having been copied by the monks and other learned scholars. But the originals have long ago crumbled to dust, been burned by fire, eaten by bugs, etc. A very few writings of some other civilizations, the papyri of the old Egyptians are still around for example. Texts inscribed in clay, cut on stone or fashioned in metal still exist. Coins, cameos, cabochons, stone seals and the like have endured for thousands of years. The point is that the creators of lapidary should treat their creations reverently: they may be around 2000 years from now!

Simple Rules for Silversmiths

  1. Don't touch silver until it has cooled.
  2. Don't lay down a lighted torch.
  3. Don't inhale the fumes of the flux.
  4. Use only copper tongs in the pickling solution.
  5. Remove all binding wire before soldering.
  6. Scrub all work before soldering.
  7. Don't rush.
  8. Work from your drawing.
  9. Use the soldering table for all soldering.

Study of Crystals

Crystallography is the scientific study of crystals and it is very important to gemologists and lapidaries. In 1912 it was found that the shape and size of the repeating atomic patterns or unit cells in a crystal could be determined by passing x-rays through a sample. This entirely new method generally called diffraction opened up an entirely new way of "seeing atoms" and studying them.

It has been found that many substances have a unit cell that exhibits all the symmetry of the whole crystal. For example, quartz sometimes called the stone of the lapidary, has been thoroughly studied by taking x-rays of quartz and studying the results.

Fossils

Fossils are remains of extinct animals and plants that have generally undergone some sort of mineralization, through the action of pressure and mineral water. Fossils are much more in evidence than some rockhounds realize.

Coal is formed of the remains of plants that lived in swampy forests. Limestone, often used as building stone, is the remains of extinct sea creatures. Dolomite is formed mostly of ocean shells. Amber, coral, chalk, oil and many other substances are fossils.

Occasionally, more spectacular fossils turn up, dinosaurs in North Dakota, frozen mammoths in Siberia and sloths in Florida are examples. But anyone can find fossils. For a beautiful miniature fossil try looking carefully at chalk, limestone or coal.

Fluorite

Fluorite has a property that makes it very useful in smelting ores. When it is present in small quantities, other minerals melt at lower temperatures. While talking about fluorite it is interesting to note that white enamel is composed of sand with about 15% fluorite added.

Granite

Granite is defined as a rock composed of quartz, feldspar and mica. However, quarry owners see 100 toms of granite as 8 lbs of aluminum, 5 tons of iron, 1200 lbs of titanium, 180 lbs of manganese, 70 lbs of chromium, etc. And to boot, enough uranium and thorium to supply atomic energy equal to the energy contained in 5000 tons of coal.

Cat Scan

The "Cat Scan," an acronym for computerized axial tomography is a sophisticated method of x-ray imaging. One of its uses is in archeology to examine mummies. This technique is said to be the most important breakthrough in Egyptology since the discovery of Tutankhamon's tomb.

Of course, much can be learned about the old Pharaohs. Their wives and others of their times were mummified. The causes of their deaths, from diseases and injuries, their life span, their use of medicine are all at least partly revealed by x-rays.

For the first time a view of those mummies newly unwrapped can reveal many things, hidden amulets of gold and semi-precious gems along with the outline of the face, old healed fractures, even the age of the death becomes known. Indeed, for instance, some of the Pharaohs even wore earrings!

Window Shopping Wisdom

Lepidolite

Difficult to polish, soft with a hardness of 4+, Lepidolite is nevertheless used by lapidaries when it occurs in massive form and has beautiful colors. It may be yellow, pink to purplish or lavender. Often found in fine-grained masses, it is used as a carving material.

In California, Lepidolite is found in the Pala district in pegmatites, occurring in pockets and fracture fillings. Micro-crystal collectors always look for it on the dumps and tailings of tourmaline and beryl mines. It is generally associated with quartz, albite, tourmaline, muscovite and spodumene.

Lepidolite sometimes contains about 30% lithium oxide (LiO) and in the Pala district, has been mined for mined for this lithium.

Some Attributes of Quartz

In his talks about quartz and its relatives, Si Fraser mentiones some of the characteristics of our old friend silicon dioxide. Besides its usual list of physical traits, a hardness of 7, specific gravity of 2.65, refractive index of 2.54, transparent to opaque colors with agate, especially, appearing in nearly any color - conchoidal fracture, hexagonal or trigonal crystal form, bull's eye interference figure, etc., etc. Quartz has certain other attributes - it is very stable chemically and physically, and appears in crystal, microcrystalline and amorphous forms. These forms are practically insoluble in acids, but are soluble in certain alkaline solutions. Quartz does not readily oxidize because its composition already has all the oxygen it needs, so it does not readily weather. It has an extremely high melting point 1600 degrees C. And is composed of two very plentiful elements silicon and oxygen, combined in very simple ways. No wonder it is so plentiful on the earth's surface, and with so many good features going for it is the beauty queen of the lapidary's eye. What would lapidaries and carvers do without it?

Is it a Nodule, Geode or Concretion?

A Nodule is a rounded mass of irregular shape, a little knob or lump of any kind of mineral. The word nodule comes from the Latin word, meaning "knot."

A Geode is a nodule which is hollow or has a cavity that may be lined with one or more minerals. The word geode comes from the Greek, meaning "Earth form."

A Concretion is a mass formed by the aggregation and precipitation of some mineral such as quartz or calcite, around a nucleus which is often a fossil or small pebble. The word concretion comes from the Latin, meaning "to grow together."

Beads and Wampum

Native American beads were made of various materials such as shell, bone, pearls, metals, porcupine quills, gumwood, pottery, teeth and seeds. When they were made of metal they were usually gold, silver or copper. Many trade beads are found with other Indian artifacts. Columbus was probably the first to bring trade beads, when he gave beads to the Indians to win their friendship. The shell bead is the most common in America and was made in many shapes such as disc, tube shaped, barrel-shaped and spherical. The shell was considered sacred by many tribes as it came out of the water. Beads were decorated in various ways, such as by carving, painting, inlaid work and even by putting skins over a portion of the bead, the more the value placed on it.

Where did the bead originate? No general answer has been obtained but beads have been found with all primitive peoples. When beads were used as a medium of exchange, they were called wampum. The majority of wampum was made of shell in a cylindrical shape, about 1/4 inch long and were used interchangeably as adornment or as a medium of exchange.

The Feel of Jade

A young Chinese, who wanted to learn about jade, went to study with a talented old teacher. This gentleman put a piece of jade into the boys hand and told him to hold on tight. Then the old man began to talk of philosophy, men, women, the sun and almost everything under it. The procedure was repeated for weeks. The boy became frustrated; when would he be told about jade? But he was too polite to interrupt his venerable teacher. Then one day the old man put a stone into his hands. The boy called out instantly "THAT'S NOT JADE!"

Black Tourmaline

Black tourmaline, in long, prismatic, six sided crystals is one of the most interesting minerals found in many granites in the Sierra Nevada. In the slowly cooling granitic magma deep under the earth, the aluminum boro-silicate that forms the tourmaline crystallizes out of the melt when the magma reaches a certain temperature, forming radiating crystals. While they do not have the gem quality of the beautiful pink and green tourmalines of pegmatite dikes, they are worthy of the interest of any collector.

Three Brothers of Carbon

One of the very common minerals in earth's crust is carbon. It is found in many compounds both in nature and in the laboratory. Carbon dioxide, a gas in the air, hydrocarbons in the oil of the earth, solid rocks such as limestone and other carbonates all are plentiful in the earth's crust. Carbon also occurs, more or less in a pure state in nature, in three different forms:

Coal, and the charcoal of burned forests contain amorphous carbon. Residues of all the earth's plants and animals contain carbon, as did the living residues that produced these residues.

Graphite is pure carbon and is found in many places in the earth's outer layer. It is hexagonal in shape and most often occurs in metamorphic rock formations. The single crystals are six sided thin plates and it is often used as an outstanding example of the relation of internal atomic arrangement influencing the gross physical properties of a material. It is soft and opaque, lower than average specific gravity 2.3, and is an excellent lubricant, fine for making pencil leads and crucibles and is extensively used in industry as a filler and in alloys.

Diamond, the third brother is rare and found in pipes or alluvial remains of these pipes. It is the epitome of hardness, heavy 3.5 specific gravity, and belongs to the cubic crystal system. It is a jewel and is used in industry as the cutting workhorse, par excellence, and is the working ingredient in all sorts of drills and abrasive tools.

Flint

Flint is a sedimentary rock occurring as fine grained nodules in chalk deposits, usually with a waxy luster and excellent conchoidal (clam shell-shaped) fracture. As flint, which is a form of silica SiO2, is hard and brittle and breaks into fragments with razor sharp edges, it was used by most prehistoric groups to manufacture instruments and tools. Flint outlasts copper and all other metals, and flint tools and weapons of early man give us record, though incomplete, of his life and habits. Many different kinds of native Americans from at least 9000 BC have left this kind of record.

In the middle of the United States, a deposit of flint, called Flint Ridge, extends from Zanesville, Ohio to Newark. This area produced material for arrowheads, spearheads and knives used over a large area of the country. Some Indians traveled for hundreds of miles and traded other goods for this flint. Even today trails to and from this deposit can be followed for great distances.

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