Chippers’ Chatter Chippers’ Chatter Newsleer of the Chesapeake Gem & Mineral Society Balmore, Maryland <chesapeakegemandmineral.org> Volume 58, Number 3 March, 2014 Program Notes Inventory from the estate of the late Dale Fisher Friday, March 14, 2014 Preview at 7:00 pm – Aucon begins at 7:30 pm sponsored by the Chesapeake Gem & Mineral Society Items to be auconed include: Equipment: Slab saws, lapping systems, cabbing units, tumbers, scales, refractometer, microscope, jewelry tools, buffing hood, soldering tools, geological tools and more Cut Stones - both faceted and cabochon Rough cung material: Top grade AAA cung rough including a large assortment of slabs Adams County PA copper rough and slabs faceng rough Minerals: Assortment of thumbnail minerals Cabinet to large sized Adams County, PA copper speciments Aucon to be held at Westchester Community Center 2414 Westchester Ave; Oella, MD (if using GPS use Ellico City) go to <chesapeakegemandmineral.org> for direcons Cash or check only Our 25th Show by Lynne Luger The date for this year’s show is Saturday, May 24th. This is Memorial Day weekend once again and we will be celebrang our 25th year! Bernie is in the process of contacng our dealers, and rent - ing tables. Fliers are being print- ed and the date is on our website and has been published in the EFMLS Newsleer. Our once a year show should be a priority for every member. Start the fun by pung the date on your calendar NOW. We’ll need lots of volunteers for the informaon table, silent aucon and children’s table as well as Fri- day evening set-up and Saturday aſternoon take-down. We’ll start asking for vol- unteers at the March meeng. Please be prepared to sign up and help out for at least an hour, give out fliers to your friends and acquaintences and definitely plan on aending.
Transcript
Chippers’ ChatterChippers’ ChatterNewsletter of the Chesapeake Gem & Mineral Society
Baltimore, Maryland <chesapeakegemandmineral.org>
Volume 58, Number 3March, 2014
Program Notes
Inventory from the estate of the late
Dale FisherFriday, March 14, 2014
Preview at 7:00 pm – Auction begins at 7:30 pmsponsored by the Chesapeake Gem & Mineral Society
scales, refractometer, microscope, jewelry tools, buffing hood, soldering tools, geological tools and more
Cut Stones - both faceted and cabochon
Rough cutting material: Top grade AAA cutting rough
including a large assortment of slabsAdams County PA copper rough and slabs
faceting rough
Minerals: Assortment of thumbnail minerals
Cabinet to large sized Adams County, PA copper speciments
Auction to be held at Westchester Community Center2414 Westchester Ave; Oella, MD (if using GPS use Ellicott City)
go to <chesapeakegemandmineral.org> for directions
Cash or check only
Unique Auction OpportunityOur 25th Show
by Lynne Luger
The date for this year’s show is Saturday, May 24th. This is Memorial Day weekend once again and we will be celebrating our 25th year!
Bernie is in the process of contacting our dealers, and rent-ing tables. Fliers are being print-ed and the date is on our website and has been published in the EFMLS Newsletter.
Our once a year show should be a priority for every member. Start the fun by putting the date on your calendar NOW. We’ll need lots of volunteers for the information table, silent auction and children’s table as well as Fri-day evening set-up and Saturday afternoon take-down.
We’ll start asking for vol-unteers at the March meeting. Please be prepared to sign up and help out for at least an hour, give out fliers to your friends and acquaintences and definitely plan on attending.
Page 2 Chippers’ Chatter – March, 2014
Members of the Eastern Federation of Mineralogical & Lapidary Societies
Affiliated with the American Federation of Mineralogical Societies.
The Chesapeake Gem & Mineral Society was established in order to al-low its members to gain knowledge and skills in various phases of the Earth Science field. Through field trips, ex-hibitions, and cooperation with other societies, we endeavor to further not only our own knowledge, but also that of the general public. Meetings are held on the 2nd Fri-day of each month except August at the Westchester Community Center, 2414 Westchester Ave; Oella, MD.. Meetings begin at 7:30 P.m. and visitors are al-ways welcome. Dues are $15 for individuals, $25 for family memberships.
Officers:President - Richard Hoff
<chesapeakegem at gmail.com>
Vice President - John Buchleitner<chesapeakegem at gmail.com>
Recording Secretary - Earle Pfetzing<chesapeakegem at gmail.com>
Corresponding Sec’y - Patty Lortie<chesapeakegem at gmail.com>
Treasurer - Steve Weinberger<chesapeakegem at gmail.com>
Directors: 2012 2013-14 Dawn Johnsson Russell Byers Cathy Purdum Steve Dyer
Editor:Carolyn Weinberger
<cscrystals2 at gmail.com>
Deadline is the 15th of each month.
Non-commercial reprint permission granted to non-profit organizations unless other-
wise noted.
ChesapeakeGem & Mineral
Society
Written in Stoneby Richard Hoff, President
Winter Weather Policy
Hey all,
Are done shoveling yet? Well, this winter has taken a small toll on us all. Due to the weather, we missed our first meeting in years. Thanks to all the phone tree operators for getting the word out.Even though Balto County Schools cancelled all classes for that Fri. it was not clear that evening activities were cancelled as well, so we notified everyone. [Ed Note: If the county schools cancel day activi-ties, evening activities are cancelled as well.] I do hope no one went to community center. If there is any question regarding a meeting please don’t hesitate to give me a call.
The board meeting was also cancelled, so we have not had a chance to firm up the budget, committee chair positions, the contest or field trips. I do not want to make important choices for the club without input of our board members. But this is being remedied and we’ll have our meeting shortly.
It’s time to start talking about are annual show at Ruhl Armory. This is our biggest event of the year. We need to arrange for committee chairs, advertis-ing, setup and teardown, auction items and giveaways, as well as volunteers.
This month we are having a very important auction of items from the late Dale Fisher. Dale was an extremely knowledgeable and generous collector who is missed by all in the rock club arena. Bernie has done his usual amazing job of getting togeth-er with Dales’ family and organizing and moving a mountain of stuff. I’m sure there will be great deals to be had. See the flier on page 1 for details. We should have lots of guests and I am sure we will all make them feel welcome as we always do!.
So if it’s still snowing and cold, get in the collecting room/basement/shop and have an adventure with your goodies and projects.
Richard
Chippers’ Chatter – March, 2014 Page 3
February Meeting Minutesfrom Earle Pfetzing, Recording Secretary
No minutes from February since our meeting was can-celled due to snow.
Get well wishes to Helen Herman, who is recovering from a very serious staff infec-tion, which required surgery fol-lowed by rehab. She’s now back at home where she continues her rehab.
Steve Weinberger took a tum-ble right after returning from Tuc-son and managed to fracture both
his left patella and right ankle. No ice involved, just a nasty misstep. He has a humungous brace on his left leg to keep the knee straight and another on his right leg for the ankle and is using a walker for support to help him get around.
Congratulations to Richard Meszler for being Rock and Gem magazine’s Lapidary of the Month for February. Well done!
Personalsby Lynne Luger
Last Call for 2014 Duesby Steve Weinberger
Time’s running out for renewing your membership in Chesapeake. The deadline for doing so is March 14th - the night of our regular meeting.
Dues remain at $15 for individu-als and $25 for family memberships (two adults and all children under 18 living in the same home). To renew, please complete the form on page 11 and submit it along with your dues. If you’ll miss the March meeting, please drop the form and your check in the mail.
We’d hate to lose you as a member!
Nibbles ‘N Noshesby Wendy & Liz Stanne
Thanks to the snow storm in February our meeting was cancelled. We hope that our members were safe and
warm in their homes.
The March meeting will be an auc-tion and hopefully, the snowstorms have ended for good by then!
Mary Chandler, Phyllis Dyer, Pa-tricia Smith and Lynne Luger (our auction quartet) have signed up to provide the refreshments for the evening.
Oldest Piece of Earth Identifiedvia Becky Kays
Scientists using two different age-determining tech-niques have shown that a tiny zircon crystal found on a sheep ranch in western Australia is the oldest known piece of our planet, dating to 4.4 billion years ago. Writing in the journal Nature Geoscience, the researchers said the dis-covery indicates that Earth’s crust formed relatively soon after the planet formed and that the little gem was a rem-nant of it.
The zircon was extracted in 2001 from a rock outcrop in Australia’s Jack Hills region. For a rock of such impor-tance, it is rather small. It measures only about 200 by 400 microns, about twice the diameter of a human hair.
You can read the full article about the discovery and process of identification at <http://news.msn.com/sci-ence-technology/rock-around-the-clock-zircon-crystal-is-oldest-piece-of-earth?ocid=ansnews11>
The zircon, a tiny black speck imbedded in epoxy, is the oldest known
piece of the Earth.
Page 4 Chippers’ Chatter – March, 2014
There were two things that attracted me to this hobby of minerals: Crystals-their shape and color and the real-ization that rocks are constantly changing. My wife and I were on a tour of Stone Mountain outside of Atlanta, Georgia when the tour guide in-formed us that parts of the granite mountain were eroding at the rate of one inch per year. It then struck me that these rocks that we live on are constantly changing. This tickled my curiosity and I had to find out more. It seems that Mother Earth, a maternal metaphor for the gentle hand of the natural forces that regulate our physical environment, in contrast with the violence off outer space, is forever reinventing herself right before our eyes and under our feet. We just have to be perceptive enough to see it and grasp some un-derstanding about what is occurring. We know this by the clues she shows us, constantly reminding us who is boss. James Hutton was a Scottish farmer and Naturalist in the late 17th and early 18th century who is considered the father of modern geology. He reasoned that the Earth was in a constant process of change. He set the bar for the notion of “the great geological cycle” of mountains being formed and eroding, forming sediment, being reformed and the cycle goes on. Geology has been built on these notions ever since. In the 20th century and especially so since the 1950’s and 1960’s a description of the Earth’s sur-face has evolved that demonstrates the Earth plates float on a highly viscous material and move at a slow rate along this material. We are made aware of this by clearly ob-servable earthquakes and tremors along the boundaries of these plates as they meet and crash into each other. The grinding and recycling materials by subduction are part of the cycle. The great Ring of Fire which is a partial circle of volca-nic islands in the Pacific Ocean gives the clearest picture of the Earth’s dynamics with the evidence of volcanoes and earthquakes. Not only does this activity demonstrate what is happening, it has been discovered that the conti-nents are moving. Scientist discovered what appeared to evidence of marine activity in mountains and other rocky formations. Theories evolved that somehow sea bot-toms were in a dynamic state and relocated their material to other parts of the earth’s surface. Theory predicted a subduction was taking place which moved sea bottom ma-terial to the magma depth and reprocessed it back up to
Earth – The Great Recyclerby John Buchleitner
the Earth’s surface. Proof of this was established by the discovery of deep trenches in the ocean bottom which was the gate location for the material to convey through
the flowing magma until it escaped through fumaroles back to the Earth’s surface usually in the form of mountains. Mountains are also formed by the collisions of the tectonic plates as they grind and push each other around. The mountains weather away and the material is moved back to the sea by streams, rivers, etc., much as Hutton predicted. One particular cu-riosity about the Ring of Fire is that the mag-ma plumes stay fixed while the plates move.
Hence, the volcanic islands move and become “old” while new ones are being formed. The behavior is similar to a production line. The activities that are involved in this recycling process involve the consumption and release of great amounts of energy. In the early years of the educational programs of engineering and science students, Professors introduced two concepts of thermodynamics that are totally intended to torment these tender minds. Enthalpy and Entropy are the evil concepts that must be dealt with. Thermodynam-ics is mostly concerned with the conversion of quantified heat energy to some useful work activity. Enthalpy is de-fined as the total energy of a system in a defined environ-ment or space. The concern is not so much for the amount of energy but with the changes in Enthalpy. Entropy is a master mind twister in that is the amount of energy lost in doing work that cannot be recovered in a reverse cycle. Hence, there is no such thing as a perpetual motion ma-chine. The implication is the amount of energy defined as Entropy in the universe is constantly increasing. Entropy is also the concept that gives time a dimension in the quan-tum world that defines events as not being reversible. The thermodynamics of the grinding and forming of our Earth involves these tricky concepts. We know that forming crystals under certain conditions of temperature and pres-sure equilibrium has to be reached. The principle of least energy argues that the system being examined must settle into a level of energy that defines when the systems reach equilibrium. How the molecules and atoms end up in the form they do is a complex question usually approached by using quantum analyses. Some calculations for this exer-cise requires thousands of hours of computer time. Suffice
continued on page 6
Chippers’ Chatter – March, 2014 Page 5
it to say at this point there are rules for generating these analyses and it takes a devoted life to apply them. We just need to know that energy is involved and the energy is obtained from the earth’s activities in the form of pres-sure and heat (temperature). When the temperature and pressure of the space that we are concerned with changes, the energy equilibrium is unbalanced and a change in the materials must occur. This process is ever ongoing and the reason why our Earth is always changing. Adding or sub-tracting energy in the space defined as our space of inter-est including sunlight, water changing phase states, wind, and all of these combined are also energy transfers which cause our changes. There are also rules that energy must be accounted for. This rule is called the Conservation of Energy. We must recognize out the outset of our little dis-cussion that energy is always involved in changing forms, shapes, colors, etc. Meta physicists have known for many millenniums that there is energy in the crystals that we discover. Over the centuries they have assigned qualitative values to vari-ous crystals that yield very human traits to their useful-ness. It is known that quartz, one of the more abundant and also attractive crystals has values associated with warmth and healing. Sometimes referred to as a pseudo-science the use of crystals and stones has been with us for many centuries. It is frequently associated with Bud-dhism and Hinduism in the virtual description of the hu-man experience and how their description of life powers operates. The energy of the stones and rocks is described as having bandwidths and affects different behaviors. The science talks of chakras, the vortex of energy of our vir-tual self that the crystals can affect in some mystical way. Sedona, Arizona is noted to be a location where many of these mythical energy vortexes exist and with the proper guidance can aid the beneficence of our existence. Quartz is said to affect every center of the human body and acts as an amplifier of the energy of the inner self. Agates relate to courage and emotions of inner confidence. Amethyst is prescribed as a stress reliever. Aquamarine clears the minds and enables more mental focusing. Garnet is used to enhance passions. Jade is associated with good luck. Obsidian clears negative emotions. Pyrite blocks negativ-ity from external sources. Modern progressivism tries to offset these mystical beliefs by arguing that they are repre-sented by no scientific proof. However, there are still many believers among us today who sense there is an energy in these inanimate objects that hones our life experience
and makes for a more responsive human being. This may be a subconscious factor in the ever hunger for the more perfect crystal. Who can really say? Some oddities to note about crystals bear mentioning. The Great Pyramid has the same shape as the termination end of a quartz crystal with the angles in contact with its base being the identical to similar angles on the quartz termination. Quartz crys-tals have electrical properties that have great commercial use. The crystals can vibrate when in contact with a source of electrical energy which make then useful for timepieces. Also, they can generate electrical impulses when mechani-cal energy is applied to them which make them useful for frequency sources in electronic circuits. There is a very fine science to using the quartz crystals for these applications the essence of which is the angles at which they are cut. The process of forming crystals begins with the magma constantly bubbling beneath our feet deep in the Earth. As this magma creeps toward the earth’s surface at the edge of the tectonic plates and begins cooling the crystals we look so passionately for begin to form. How they form and how big they get depends on how close the magma is to Earth’s surface. We know the cooling rate determines the size of the crystals. The cooling that occurs near the Earth’s surface will result in the formation of smaller crystals than the magma that is cooling in deeper penetrations. The crys-tal formation near the Earth’s surface is called an extrusive process and the crystal formation deeper in the surface is called an intrusive process. The magma is largely a silicate material mixed with elements created during the nucleon-ic formation of the Earth. What type of crystals and mate-rials we discover from this magma depends on the amount of these different materials present in the magma during the cooling period. There are three recognized types of magma usually distinguished by where they originate and the amount of silica present in their composition. Basaltic magma has a relatively low silica content and is found in mantle upwelling; andesitic is middle silica content found in crustal convergence in subduction zones; Granitic has is high silica content and is found in root zones of mountain belts in the continents. The viscosity of these magmas in-creases with the amount of silica present in their content. It is interesting to note that silicon and oxygen are two of the most abundant materials found in the crust. The tem-perature and pressure conditions enable the formation of the silica molecule which is designed to be very convenient
continued on page 7
The Great Recyclercontinued from page 4
Page 6 Chippers’ Chatter – March, 2014
for adding other elements which favors the formation of so many other silica based materials. What is the significance of all of this understanding? Crystals unearthed by pros-pectors are messages. The messenger is the magma that generated the beautiful little items. The magma traveling on its way to the Earth’s surface may go through several transformations of melting, partial solidifying and melting again. When it does this it gives clues as to what is happening beneath our feet. Energy needed for the formation of the materials and minerals begins with the dropping of temperatures as this material cools. Subatomic particles form by laws as we know in the quantum world. Our Earth’s core is a molten metallic ma-terial that has temperatures of up to 12,000 degrees. As the material works its way to the surface it cools and ele-ments group into pockets depending on their relative state (liquid to solid) changing temperatures in super saturated solutions and form the crystals we can examine. Energy is the constant of all these processes. Energy is needed for changing these state phases. The pursuit of how these el-emental materials became distributed throughout this fan-tastic subterranean world is still looking for answers. We know a few things. Silica is the predominate material. It has a wonderfully designed crystal structure (SiO 4) allows attachments of other elements which changes color and crystal formations creating the beauty we admire. Thermo-dynamics govern how the energy is distributed in all of this mineral making process. The environmental temperatures and pressures define the equilibriums required for these mineral to exist in. This process is constantly going on. Continents are moving, ocean floors are subducting, the great conveyor belt is always turned on. The North Ameri-can continent is moving E by NE at about 3 inches per year. It is opined that this conveyor belt works because of the different energies associated with different temperatures. Thermodynamics also predicts that somewhere down the time road, this Earth will cool, the magnetic field will fade, and there will be insufficient energy left in its core to sus-tain life and the subatomic particles will be returned back to the universe for recycling. However, this event is billions of years away. Now that we have some inkling that energy from the Earth’s core provides the reason for our existence on this planet, and we also sense that there are some rules about how this energy works in our favor, we will try to grasp what is happening to this little green dot in the universe.
The movement of the plates that we know about is reveal-ing lot of previously unknown events in the Earth’s history. The Circle of Fire tells about the subduction phase of the recycling. The Himalayan Mountains are revealing other clues about the clashing of two of the plates, the Asian Plate and the India plate. The India plate traveled over a plume that shaved some material off of the bottom. It then picked up a little more momentum and crashed into the Asian plate causing the mountains to grow up and con-tinue to increase in height. The growth of these mountains contributes to the monsoons season so well known in In-dia. The rain sucks up carbon dioxide and forms carbonic acid which help the degradation of the mountains and the rushing water moves the crumbled material down to the rivers, Ganges, Indus and rivers in China. Some think as these mountains grow in increase the effects on the mon-soons it might cause a great consumption of atmospheric carbon dioxide which will contribute to a lowering of the Earth’s temperature. Great planet cooling is much more devastating than warming effects. The long term effects of the movement of the tectonic plates are still be being stud-ied and analyzed. Evidence from the Earth as it was 250 billion years ago is scant because of this recycling process. At this point in discovery theory rest largely on opinion and supposition. As our ability to view what is occurring im-proves the explanations become more concrete. Crystals are important in this discovery process. The behavior of crystals has been studied for a long time. We have learned how to categorize them as to shape, content, color, etc and the amount of energy they possess and how much energy to takes to make and dissolve them. Looking at crystals and rocks in general can tell us the dif-ferent temperatures involved in forming these minerals. We know olivine forms at high temperatures and quartz forms at lower temperatures. Examining sedimentary rocks gives us his evidence of our history by looking at the stratified materials present in these formations. The clues are there, the evidence is there, we have to continue to learn how to read the data and interpret its meaning. We have learned that an ordered thermodynamic world with the presence of water can give life in a planetary environ-ment. Isn’t it kind of exciting to know your feet are never still, you are always moving and we are part of a constantly recycling process?
The Great Recyclercontinued from page 5
Chippers’ Chatter – March, 2014 Page 7
The geology of the Grand Canyon Area exposes one of the most complete and studied sequenc-es of rock on Earth. The nearly 40 major sedimentary rock lay-ers exposed in the Grand Canyon and in the Grand Canyon
National Park area range in age from about 200 million to nearly 2 billion years old.
But the Grand Canyon itself is much younger. The Na-tional Park Service’s Grand Canyon website page on geol-ogy says that “The Grand Canyon itself is a late Cenozoic feature, characteristic of renewed erosion during this time. Vigorous cutting by the snow-fed Colorado River carved the Canyon’s depth.” But the timing of the canyon’s forma-tion has been vigorously debated. In one view, most of the canyon was carved by the Colorado River relatively recent-ly, in the past 5–6 million years. Alternatively, the Grand Canyon could have been cut by precursors in the same lo-cation and to within about 200 m of its modern depth as early as 70–55 million years ago.
“I think we’ve resolved the 140-year-long debate about the age of the Grand Canyon,” says Karl Karlstrom, a geologist at the University of New Mexico in Albuquer-que. He and his colleagues described the findings in a pa-per in Nature Geoscience.
The debate focuses on when exactly the Colorado River began cutting through those layered rocks, forming the 3-dimensional chasm that tourists swarm to today. Canyon experts had generally thought that the chasm formed around 5‒6 million years ago. But over the past few years, several studies have marshalled a range of geologic evidence to suggest that the canyon could be tens of millions of years old. Karlstrom and his team find that parts of the canyon could be tens of millions of years old, but that the canyon as a whole is much younger.
Scientists can date a canyon’s formation with geo-chemical techniques that measure the temperature of rocks over time. The deeper a rock is buried, the warmer it is. When erosion removes the overlying rocks, as when a canyon forms, the rock is moved closer to the surface and cools down.
Grains of the mineral apatite contain several lines of evidence that can be used to trace a rock’s temperature history. For instance, the decay of radioactive uranium within the apatite produces helium atoms, which diffuse out of the mineral depending on how warm the rock is. In 2012, geologists Rebecca Flowers of the University of Colorado Boulder and Kenneth Farley of the California Institute of Technology in Pasadena used this technique, among others, to conclude that some now-exposed rocks in parts of the canyon must have been cool for as long as 70 million years.
In their study, Karlstrom and his colleagues used apa-tite fissiontrack dating, track-length measurements, and apatite helium dating to study rocks from the length of the Grand Canyon. The team found that two stretches near the canyon’s middle are indeed quite ancient: the eastern Grand Canyon is 15‒25 million years old, and an-other stretch downriver is 50‒ 70 million years old.
But the researchers also found that two other seg-ments—Marble Canyon, the farthest stretch upriver studied, plus the westernmost Grand Canyon—were carved far more recently. “Different segments of the can-yon have different histories and different ages, but they didn’t get linked together to form the Grand Canyon with the Colorado River running through it until 5 to 6 million years ago,” says Karlstrom.
Karlstrom and his colleagues argue that while the Hurricane and Eastern Grand Canyon segments were originally sculpted by different rivers, the Colorado took over the job in the past six million years, joining the dis-parate canyons and carving them wider and deeper.
The debate is not settled. Brian Wernicke, a geosci-entist at the California Institute of Technology, points out that interpreting thermochronology data, especially fission-track data in terrain where erosion carves down-ward as well as sideways, is notoriously difficult. We’ll look for more on this.
The Geology of the Grand Canyonfrom MAGS Rockhound News, February 2014
Page 8 Chippers’ Chatter – March, 2014
A few of the world’s gemstones are known from only one or two localities. Some of these, such as larimar from Barahona Province, Dominican Republic and thomsonite, from Minnesota, are nearly opaque and are best cut into relatively inexpensive cabochons. More exotic, transparent rarities in-clude red beryl from Juab Co., Utah; pink diamonds from the Argyle deposit, in Western Aus-tralia; and violet topaz, from the
Northwest Frontier Province, Pakistan.
For my money, the most beautiful rare gem comes from an area in northeastern Tanzania, near Mt. Kiliman-jaro. Consisting of several contiguous mining concessions, the Simanjiro tanzanite district, in the Merelani Hills, was not even discovered until the early 1960s, when a speci-men showed up in a curio shop in Arusha. Since then, Merelani has been the world’s sole producer of gem tan-zanite, in quantities that have made it one of the great-est of modern gem occurrences. In the late 1960s, Tiffany and Co. named and popularized the gem, but problems with mining in Tanzania caused the supply to dry up in the early 1970s. Since then, production has been spasmodic at a few million carats per year. Reserves currently are estimated to last for 2 to 3 decades. In 2002, the Ameri-can Gem Trade Association named tanzanite as one of its three official December birthstones (along with turquoise and zircon). Besides tanzanite, Merelani also yields em-erald green tsavorite garnet (a variety of grossular), di-opside, tourmaline, and tremolite, as well as blue apatite and lavender to pink axinite-(Mg). The world’s best free-standing graphite crystals, as well as fine specimens of pyrite and prehnite, also make Merelani a Mecca for min-eral lovers. What is it that makes this deposit so special?
Like many valuable gemstones, tanzanite is the transparent, colored variety of a common mineral. Zois-ite, a member of the epidote group, is a complex silicate containing calcium and aluminum. It most commonly oc-curs as gray-green or brown prismatic crystals or masses in metamorphic rocks and altered igneous rocks, where it may occur in veins and joint fillings. Although it’s used
as a gemstone, it is not especially hard (at 6 to 7). The fact that it’s brittle and has a perfect cleavage also com-plicates its use. Tanzanite should never be subjected to sudden temperature changes or abrasives.
Also like many other valuable gemstones, tanzanite is colored by an impurity. The blue to violet color is attributed to the presence of trivalent vanadium (V+3). A pink gem zoisite, called thulite is colored by manganese. Gem tanza-nite crystals up to 22 cm. (9 inches) long are known, but crys-tals typically measure a few cm. long. Tanzanite is unusual in that heat treatment to enhance its color is not considered objectionable. Although natural blue gem quality tanzanite does occur, it is very rare (though the color improves with depth of min-ing). Most freshly mined stones have a green, yellow, or brown cast that, for many buyers, makes them colored zoisite, rather than tanzanite. To achieve the typi-cal saturated blue or purple-blue color, stones are heated to just below 400°C for a couple of hours. Problems with exploding inclusions and cracking can be avoided by cutting stones to remove flaws before treatment. There are several ways to identify treated stones, but most people don’t bother, since 99.9% of the stones are treated anyway (jckonline.com). It should be noted that tanzanite is strongly trichroic, mean-ing the color varies with direction in the stone. Crystals com-monly are carefully oriented before cutting, to maximize the saturated blue color. Its color also varies with the type of lighting: in incandescent light, tanzanite has a more violet color; in fluorescent lighting, it tends to be more blue. Rarely, stones are coated with a cobalt compound to enhance the color, but this, by law, must be disclosed in the U.S. market, where most tanzanite is sold.
The geology of the Merelani tanzanite deposits has been thoroughly described. A good summary is provided by Wilson, et al. (2009), from which this account is derived. The rarity of tanzanite (and tsavorite garnet) reflects the fact that the geology of the Merelani Hills area is unusu-al and complex. The rocks are all high grade Proterozoic
The World’s Newest Birthstoneby Bob Carnein, from Lake George Gem & Mineral Club, December 2013
continued on page 9
Chippers’ Chatter – March, 2014 Page 9
If you want to know whether you have sodalite, lapis or imitation lapis, look for pyrite inclusions. Lapis-Lazuli will have pyrite inclusions. Sodalite does not have pyrite inclusions. In imitation Lapis the inclusions are golden flakes not pyrite crystals.
Lapis Lazuli is a gemstone with a rich blue color. It has a hardness of 5-5- 1/2, is com-posed of sodium aluminum sili-cate with some sulphur. Most of the properties of lazurite are sim-ilar to those of sodalite, but the association of pyrite with lazurite determines the identification.
Sodalite is composed of sodium aluminum silicate with chlorides. It is 5- 1/2 to 6 on the hardness scale and the color is usually blue but may tend to-ward white, grey, yellow or red. It is associated with other feld-spathoids, so called because they resemble feldspars but are of a slightly different compositing.
When working Lapis to a polish it requires fine sand-ing to prevent pyrite inclusions from protruding. Leather may be used with chrome oxide for polishing. Sodalite, on the other hand polishes perfectly on felt with cerium oxide, after a fine job of sanding.
A drop of Hydrochloric acid is good for testing lapis-lazuli. A drop of it on the blue stone creates an odor of hydrogen sulfide. On the white areas of the stone it usu-ally effervesces because the white is usually calcite. This test will distinguish Lapis from Sodalite.
metasediments. Tanzanite occurs at the centers and edges of pockets or pods of epidote-quartz-pyrite rimmed by a
graphite rich layer and alternating bands of limonite and epidote. The pods or pockets occur along the crests of northeast-plunging folds, where stretching of quartz veins and sedimentary layers pro-duced sausage-shaped boudins. On average, tanzanite rich pods occur every 3 to 7 meters along the strike, over an area measur-
ing 2 km wide and 8 km long. The presence of abundant graphite, sometimes as free-standing crystals, indicates that a black carbon rich shale was one of the original pre-metamorphic sediments. Shales containing organic carbon often concentrate vanadium. As this and other sediments were deformed and heated, fluids are thought to have re-moved some of the vanadi-um and redeposited it in the quartz veins at fold crests. Tanzanite and other gem minerals crystallized from the circulating fluids as the quartz veins underwent sev-eral stages of deformation.
Tanzanite reserves of more than a hundred mil-lion carats, worth several billion dollars, promise to provide Tanzania with an important source of in-come for decades to come. Current wholesale prices of cut stones average several hundred dollars a carat, and the businesses of mining, cutting, treating, and market-ing the gemstones employ an estimated 50,000 people. Who knows: if you’ve been really good this year, you may receive one of these rare gems in your Christmas stocking.
Reference Cited: Wilson, W.E., et al., 2009, Famous mineral localities: the Merelani tanzanite mines: The Mineralogical Re-cord, vol. 40, no. 5, p. 346-408.
Tsavorite GarnetMerelani Hills, Tanzania
A rare pink tanzanite
Newest Birthstonecontinued from page 8
Telling Lapis Lazuli from Sodalitevia the Glacial Drifter, February 2014
Closeup - Pyrite inclusions in natural Lapis Lazuli
Closeup - Golden flakes in Gilson created Lapis
Page 10 Chippers’ Chatter – March, 2014
Perlite is not a trade name but a generic term for naturally occurring siliceous rock. Perlite is an amor-phous volcanic glass that has a relatively high water content, typically formed by the hydration of obsid-ian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an in-dustrial mineral and a commercial product useful for its light weight after processing.
The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume. This expansion is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600°F (871°C), the crude rock pops in a man-ner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles which account for the amazing light weight and other exceptional physical properties of expanded perlite. This expansion process also creates one of perlite’s most distinguishing charac-teristics: its white color.
While much perlite rock is a light gray, it’s color changes to white after expansion. Expanded perlite can be manufactured to weigh as little as 2 pounds per cu-
bic foot making it adaptable for numerous applications. The expansion process will control many of the variables of the final product. In most instances (though not all) perlite is expanded in vertical furnaces. When the pro-cessed, unexpanded perlite is introduced into the fur-nace it falls down towards the heat source. As it falls it begins to expand becoming buoyant in the air stream running through the system. The furnace operator can control the density of the finished product by adjusting the temperature and air flow in the furnace.
New Mexico continues to lead the country in per-lite production with the largest output of six producing states, and the main markets for New Mexico’s perlite is used in building construction, as filter aids, as a filler, and in agriculture.
Perlitefrom The Beacon, via Glacial Drifter, February 2014
Page 11 Chippers’ Chatter – March, 2014
Auctions - Lynne Luger and Bernie Emery
Directory (address changes) Patty Lortie Field Trips - Brad Grant
Greeters - Al Pribula, Earl Pfetzing
Hospitality - Liz & Wendy Stanne
Committee Chairpersons
Mineral of the Month - Jim Hooper
Personals/Announcements/ Sunshine - Lynne Luger and Patricia Smith
Programs - Richard Hoff, Keith Kaneda & Tony Wilner
Safety - Johnny Johnsson
Show - Bernie Emery & Lynne Luger
Showcase - Steve Dyer
Telephone Chain Lynne Luger Phylllis Dyer Dawn Johnsson Mary Chandler Liz Stanne Wendy Stanne
Please complete this form and include it with your membership renewal.
Individual ($15)____________ Family ($25____________
Names of Members:________________________________________Birthday (M/Day)________________
Hobby Interests (see below):____________________________________________________
Hobby Interests: (Please use numbers in the spaces above) 1. Lapidary 2. Jewelry 3. Minerals 4. Fossils 5. Microminerals 6. Field TripsMail or give to: Steve Weinberger, PO Box 302; Glyndon, MD 21071-0302. Make checks payable to “Chesapeake Gem & Mineral Society”
2014 Chesapeake Dues Renewal
Page 12 Chippers’ Chatter – March, 2014
Carolyn Weinberger PO Box 302 Glyndon, MD 21071-0302
Upcoming EventsMarch; 14: Chesapeake auction meeting begins at 7:30 pm. See page 1 for details. 15-16: 50th Annual Montgomery Co. Gem & Mineral Show. Discount coupon on page 10.
20:
29-30: Philadelphia Mineralogical Society Show and EFMLS Convention. LuLu Temple, Plymouth Meeting, PA.
