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Robert William "Bob" Jones
(1926-2024)
The mineral community has suffered a great loss with the passing of noted author and lecturer Bob Jones at the age of 97. He was active in the mineral community for over 65 years and was perhaps its greatest ambassador, inspiring hundreds, if not thousands, to start collecting minerals.
For the complete Obituary: Click Here
As you may already know, the theme for our 2024 Tucson Gem and Mineral Show® is “Pegmatites: Crystals Big and Beautiful”. But you may be wondering, “What are pegmatites, and why did we choose them as our Show Theme”.
Unless you have taken at least one geology class, you may not know what a pegmatite is, and why pegmatites produce some of the most awesome mineral specimens in the world. So, I thought it might be helpful to explain what pegmatites are, how they form, and why that process produces such large and spectacular mineral crystals.
It all starts deep in the earth, generally in a region where two crustal plates are smashing together in what is called a subduction zone. When one of the plates is comprised of relatively thin, dense oceanic crust that is converging with a thicker, less dense continental crust plate, the ocean crust “slab” plunges beneath the continental crust and its underlying mantle rock.
Figure 1: Diagram of typical subduction zone, showing oceanic crust and mantle lithosphere plunging beneath a continent Source: Subduction-en.svg from Wikimedia Commons by K. D. Schroeder, CC-BY-SA 4.0
The ocean crust basalts and gabbros have been extensively altered by contact with ocean water and circulating hydrothermal waters. It is rich with water-bearing minerals (clays, chlorites, serpentine, etc.), and carbonate minerals like calcite and aragonite. The basalts and gabbros are overlain by water saturated oceanic sediments rich in clays and carbonate minerals. As these subducted rocks sink deeper into the mantle, they are heated and compressed causing them to release water and carbon dioxide.
At those conditions water and carbon dioxide behave very differently than they do near the surface. They become “supercritical fluids” that have the density and dissolving power of a liquid, but flow as freely as a gas.
So, they move easily between the mineral grains of the oceanic crust, the mantle into which it is being thrust, and the continental rocks overlying the subduction zone. As they migrate upward, they leach elements from the rocks through which they pass, and when they reach the igneous, metamorphic, and sedimentary rocks of the crust, they also bring the heat they absorbed from the mantle beneath it. The hot fluid makes the crustal rocks melt more easily to form magma.
Figure 2: This is migmatite, a rock that is transitional between a metamorphic and igneous rock. The dark banded gneiss portions (“melanosomes”) are residual metamorphic rock that have begun to melt, releasing a granitic magma which collects in seams and cross-cutting fractures that form a collection network of light-colored “leucosomes” that allows the new magma to “drain” out of the rock. Because of its lower density it begins to rise.
This magma is generally of granite or granodiorite composition that eventually rises and crystallizes into minerals such as feldspar, quartz, micas, pyroxenes, and amphiboles. Under certain conditions, the magma may reach the surface and erupt as a volcano. But more often it “stalls out” before it reaches the surface and forms a large mass of igneous rock called a pluton.
It stalls when it has crystallized enough to make it too “stiff” to flow easily, and its density approaches the density of the surrounding rocks. But there is still a significant proportion of the original magma that has not crystallized. This residual liquid continues to move upward and is enriched in “incompatible” elements that do not easily “fit” into the silicate rock-forming minerals crystallizing in the pluton.
The fluid that accumulates at the top and margins of the pluton contains a higher percentage of water and other volatile compounds than the original magma and may carry large concentrations of normally rare elements. Because it is dominated by those volatile compounds, it may collect in relatively large water-filled voids above and to the sides of the pluton (see Figure 3).
Under the right conditions, it begins to crystallize inward from the walls of those “veins” and cavities, and because it contains a lower concentration of rock-forming silicates, fewer crystals “nucleate”, so the crystals have more room to grow than they would in the pluton. That is a pegmatite.
Figure 3: Fluid collecting near the top of a cooling granitic pluton fills and expands fractures and voids and eventually crystallizes pegmatite veins and pods in the top of the granite and the surrounding host-rock.
Modified after figure 2 in Breaks, F.W., Selway, J.B. and Tindle, A.G., 2003, Fertile peraluminous granites and related rare-element mineralization in pegmatites, Superior Province, northwest and northeast Ontario: Operation Treasure Hunt; Ontario Geological Survey, Open File Report 6099, 179p.
If you took a geology or earth science class, you probably learned that the slower a rock cools and crystallizes, the larger the grains grow. Let me burst that bubble. Much recent research indicates just the opposite for pegmatites. A normal pluton may take thousands to tens-of-thousands of years to completely crystallize. It is now thought that a pegmatite may completely crystallize in years or months.
The reason that pegmatite crystals grow so large is that there are far fewer crystals that nucleate (start to grow) than in the same volume of magma, because the concentration of dissolved mineral matter is much lower. And the crystals have room to grow large, with well-defined faces, because they are crystallizing into a water-rich fluid filling the cavity or vein. Extreme examples include the 30+ foot-long spodumene crystals found in the Etta mine near Keystone, South Dakota in the Black Hills (http://www.mineral-exploration.de/mepub/etta.html).
The pegmatite-forming fluid is also greatly enriched in rarer elements like beryllium, phosphorus, boron, cesium, lithium, tantalum, niobium, zirconium, etc., so it also crystallizes large crystals of beryl, apatite, tourmaline, spodumene, zircon, muscovite, lepidolite, etc. that are often highly colored by the various metals that also became concentrated in the fluid.
The vivid colors contrast nicely with the lighter colored white, grey, or tan feldspars and quartz that they grow upon. The rapid crystallization also makes the fluid composition change rapidly, so that minerals like tourmaline, beryl, and micas may have strikingly beautiful zoning.
The pegmatite-forming processes, therefore, may produce large, well defined, and colorful crystals of uncommon minerals growing on a light-colored matrix of quartz and feldspar (which may also form large well-defined crystals of multiple habits) – creating spectacular mineral specimens, or large, clear, colorful crystals suitable for faceting top-quality gemstones.
And now you know why we chose Pegmatites as our theme for the 2024 Tucson Gem and Mineral Show®! Be prepared to see some awesome specimens in February.
© 2022 Xpo Press, Inc. and the 2023 Tucson EZ-Guide. Reprinted with permission. All rights reserved.
Huge drusy quartz specimen from Brazil on exhibit at Tucson, Photo Helen Serras-Herman
This elaborate title Silica – Agates & Opals & Quartz- Oh My! is the theme for this year’s 68th Annual Tucson Gem & Mineral Show® sponsored by the Tucson Gem & Mineral Society. The show is held at the Tucson Convention Center, February 9-12, 2023. Lapidaries and collectors can find many agates, opals, and quartz specimens at that show, as well as spread throughout all the gem and mineral shows in the Tucson 2023 Showcase.
The title hints at the chemical composition of silica (SIO2) binds quartz, agates, and opals together. Quartz is one of the largest mineral groups, with over 100 different varieties. Quartzes are among the most popular gem materials utilized by lapidaries and gem carvers worldwide. Their hardness, wide range of textures and color varieties, crystal sizes, durability, availability, and often affordability, make the quartz family of gemstones irresistible and most attractive.
Large rose quartz spheres on exhibit at Tucson, Photo Helen Serras-Herman
Quartz is divided into two main groups: crystalline and crypto-crystalline (crystals too small to be seen under the microscope). Crystalline varieties include rock crystal, amethyst, ametrine, and smoky quartz, where crystals are frequently well-defined with terminations, often occurring in clusters, and can range in size from thumb-size to mega-crystals. The crypto-crystalline varieties include the chalcedony group, agates, jaspers, flint and chert, and chalcedonic replacements, such as tiger eye or petrified wood.
Agate and white drusy quartz, gem sculpture “The Visionary” by Helen Serras-Herman, Photo Michael J. Colella
The hardness for all quartzes is 6.5-7.0 Mohs. Quartz is usually considered the benchmark that separates hard stones from soft ones. The crypto-crystalline varieties are somewhat lower in hardness than the crystalline varieties, but they gain in strength as the hidden, fine-grained structure of microscopic interlocking crystals makes these varieties more compact and tough. The hardness is high enough to allow for intricate carvings and engravings, high polish, and good wearability for jewelry pieces. The crypto-crystalline varieties commonly occur in veins, nodules, massive, and drusy or botryoidal crust formations.
We slabbed this complete agate nodule. It is now part of the Carnegie Museum of Natural History collection for education. Photo Helen Serras-Herman
Opals are another form of silica, but they differ from quartz because opals are non-crystalline silica with high water content, usually 3-20%. Opals have a different structure consisting of closely packed round spheres of silica of fairly regular size. Light reflects and refracts and causes interference and diffraction as it travels through the spheres. The different size spheres produce different colors.
This extraordinary 3.25-carat black opal, from Lightning Ridge, Australia, cut by Andrew Herman, displays chatoyancy in addition to play-of-color. Photo Helen Serras-Herman
Black and white opals are famous because they display the optical phenomenon, play-of-color. Boulder opals display the same seams of opal resting on or penetrating the ironstone matrix, and many Mexican fire opals produce the same.
Blue Peruvian opal is a beloved exotic common opal featured in these earrings. Photo Helen Serras-Herman
There are many opal varieties, qualities, and prices to match our aesthetics and budget. I love working with and showcasing unusual opals. I also find irresistible carving exotic common opals, which, for the most part, do not show play-of-color. Their striking body colors — neon blue, pink, purple, yellow, green, and bands and stripes — produce breathtaking scenic patterns. Varieties of exotic common opals include blue and pink Peruvian opal, ice-cream opal, Morado opal, bertrandite (Tiffany Stone), candy-stripe and Utah lace opal, dendritic opals, yellow, and many green opals. Customers find these exotic pieces alluring and fascinating.
There is a certain amount of heat sensitivity for all of the quartz materials during carving, sanding, and final polishing. That danger is somewhat reduced in the chalcedony varieties. There is little to no cleavage problem, however, directional and varying hardness within the material may be a problem in the polishing stage and may produce a rippled finish if not enough care has been taken during the sanding stages. Natural fractures are common, and it is best to work around them or saw the material right down the fracture line.
Lapidaries and carvers often achieve stunning design combinations by taking advantage of color variations, dendritic inclusions, outside rind and matrix, and contrasting surface textures — smooth and drusy.
Ametrine quartz with its two bold colors is a favorite among carvers.
This one is carved by David Christensen, Photo David Christensen
I am often asked whether there is a difference in carving opal compared to other colored stones. There are no fundamental differences in carving any gemstone. The lapidary steps are generally the same: grinding, sanding, more sanding, and final polishing. That being said, each material has a critical lapidary grit stage depending on the material’s hardness and uniformity.
What makes cabbing and carving opals differ from other gemstones is that the precious opal bands are often hidden deep into the stone and must gradually be revealed. The color bands may also be very thin and vanish in a flash with aggressive grinding, therefore, a slower grinding approach of “grind and look, and look some more” is highly recommended. My husband, Andy, loved the “treasure hunt” segment of cutting opals — looking for and exposing the color bands.
I hope you will not miss the 68th Annual Tucson Gem & Mineral Show®. Besides the over 250 fabulous dealers, stop by and enjoy all the amazing collections brought in by museums and private collectors as guest exhibits honoring the show’s theme. My guest exhibit case will showcase my “Gem Portraits in Quartz”, and I will be present at my Gem Art Center/Helen Serras-Herman Booth #1601 in the Ex Hall.
Huge amethyst geodes are always Tucson’s showstoppers. Photo Helen Serras-Herman
Helen Serras-Herman, a 2003 National Lapidary Hall of Fame inductee, is an acclaimed artist with 40 years of experience in unique gem sculpture and jewelry art. See her workat www.gemartcenter.com and her business Facebook page at Gem Art Center/Helen Serras-Herman
COVER PHOTO: This portrait of George Washington in a 10.5 lbs amethyst will be on exhibit at the 68th Annual Tucson Gem & Mineral Show®. Photo Michael J. Colella
I hope you all are looking forward to our upcoming TGMS Show…it’s only four months away, so we need to get planning for how we are going to enjoy…and contribute…to the effort!
The theme of our 68th TGMS Show is “SILICA - Agates and Opals and Quartz, Oh My”, designed to appeal to a very broad spectrum of collectors and mineral enthusiasts. These are some of the most widely collected mineral groups and I’d wager that +95% of collectors’ first specimen fits that bill! They are also some of the most colorful, diverse, economically reasonable…and self-collectable species around. I’d guess that many of you have specimens you have collected on personal or TGMS sponsored field trips. In her case last year, Carol Johnston showed off a couple of real cuties she collected on trips over the years! (I was next to her while she dug that sweet Japan Law Twin on a Stem…unfortunately she turned down my offer to buy it on the spot!)
So what’s this all leading up to?
As you probably know, with the expansion of the TCC and post-Covid dealer losses, the Show Committee and Society Board have decided to play to our unique strengths and double-down on our commitment to the educational lifeblood of our Show - exhibits and programs. (Sidebar here to salute our Dealer Chairs’ efforts to fill as much of the expanded new dealer space as possible…that’s what pays the bills.) This means getting the most bang out of our exhibit space possible…which I am hoping can mean more TGMS member participation as exhibitors. I would very much like to dedicate a “pod” of exhibit cases to TGMS member exhibits…and given our theme, I believe we can turn out a very good showing and perhaps even stimulate some new memberships when people see you can actually still dig nice specimens yourself. Show time is busy time for many of us, but would point out that many of us still manage to put something in most years and we will do whatever we can to make it easy for you. We can get the cases lined and if someone has a graphics bent and is willing to volunteer, perhaps we could get TGMS standard labels for the cases in the pod.
The minimum pod consists of 6 cases (4 x 48” + 2 x 66”) but that can be adjusted if a 30” case is more your speed…and we can make the pod bigger with more cases, or put in a TGMS group-shoot case if someone wants to organize contributions from several members. I can’t volunteer to be that someone, but I will kick this off by volunteering a case of Mexican quartz…and will do my best to twist Les Presmyk’s arm to exhibit some of the pieces that illustrate his Arizona Quartz article that will appear in the January-February “TGMS Show” issue of Rocks and Minerals Magazine. Marie Huizing features our Show theme every year!). Maybe we can get Carol to reprise her exhibit of last year…fleshed out with this year’s finds?
For those who simply don’t have the time…or think they don’t have the right rocks…there are still many opportunities to help out with the Show and have a great time in the process. One of the things that sets our Show apart is the friendliness of our TGMS volunteers…for years our dealers, exhibitors and the general public tell us how much they like the personal touch TGMS people give. If you are a “people person”, and a TGMS Member, volunteer for set-up or take-down security, dealer and exhibitor registration, traffic guidance, the information booth…or bringing refreshments to our overworked office staff! If you are more of a “doer”, volunteer with Robert Crowell and Elaine Hughes for case set-up and take-down, Kent Stauffer’s riser and liner team, Tim McClain’s general “fix what needs fixing” crew …or bringing refreshments to our overworked office staff! (Getting the idea there’s a theme there? Pat McClain, Rose Marques and Marilyn Reynolds put in unbelievable hours on the Show - they can use refreshments…or help…at almost any time before, during and after the Show!)
At TGMS, we do a lot of “digging”…so please Dig In here…start getting ahead on your sleep now, and get ready for another amazing Show. Oh My!!
The fern fossils from St. Clair, Pennsylvania are world famous. These plant fossils occur in black shale matrix, and have a characteristic white coating of the mineral pyrophyllite. These fossils are about 300 million years old, dating from the Pennsylvanian Epoch of the Carboniferous Period, when the great anthracite (aka, hard coal) deposits formed in the Alleghany Mountains. The fossil plants are associated with the coal beds, since coal is the product of thick accumulation of decayed and compacted plant material.
The town of St. Clair, Pennsylvania
The borough of St. Clair was established in 1850, in the Commonwealth of Pennsylvania. It is located in Schuylkill County, in the Southern Coal Region, just two miles from Pottsville, the county seat. Today, St. Clair has just over 3,200 residents.
Map of Pennsylvania and Schuylkill County
St. Clair is my husband’s hometown. He was born and raised there, the oldest of five siblings. His father was a coal miner who worked almost his entire life – from the age of 11 - in the underground anthracite coal mines, until they closed in the early 1950s. He, like so many other coal miners, died from black lung in his mid-70s.
My husband, Andy Herman, left St. Clair after graduating high school at 17, and has only returned to visit family. Andy had a wonderful collection of local minerals and fossils that he had assembled during his childhood, but while he was away serving in the US Army, his parents got a 30-day notice from the mine company to vacate their home, as the surface area was being stripped by the big shovel for the underlying coal. The entire collection vanished.
When I first visited St. Clair in the mid 1990s, primed with my husband’s description of the area’s devastation and images from movies about desolation around the coal mines, I was surprised to see the surrounding hills (many of which were tailing piles from the mines) had been mostly reclaimed by trees and vegetation. However, a closer look showed that the ground under the trees was covered with black coal residue. Andy remembers the black coal scum that used to flow in the Mill Creek, which runs through the center of St. Clair. Now, it has mostly been cleaned up.
This beautiful, large St. Clair fern fossil specimen in our collection is 2 feet, 5 inches wide and 17 inches tall, with visible fossils on the both sides.
One day, during a visit in 2007, we were driving around town with my husband’s brother, Steve Herman, who sadly passed away 2 years ago. We were on the Burma Road where their old house used to be, now a wasteland left behind by the Reading Anthracite Coal Mining Company, when he asked me if I wanted to visit the fern fossil beds. “Sure”, I said, “let’s go.” “It’s not too far from the road”, he said. “OK”, I said, “no problem, but I am in flip flops, not hiking shoes.” The hike took us about a mile from the road and passed by the shooting range, which made me even more uncomfortable.
My husband collected a few St. Clair fern fossil specimens. Everywhere on the trail, up and down the hill, fern fossils covered the ground.
When we reached the fossil beds, I truly wasn’t prepared to the sheer numbers of the fern fossils lying there. Everywhere on the trail, up and down the hill, fern fossils covered the ground. We had no bags or buckets, as this was not a pre-arranged rockhounding trip, so we used our hats and T-shirts to carry out as many fossils as we possibly could. And since we had already moved to Arizona, we had to ship our treasures back home.
Most St. Clair fern fossils occur on black shale matrix, and show a characteristic white coating of the mineral pyrophyllite. On some occasions, there is a yellow coating.
Andy and his brother, Steve Herman, examine the fern fossils
A few years earlier, we were participating at the Macungie Gem & Mineral show, hosted by the Pennsylvania Earth Sciences Association, and one of the dealers, a fossil collector and teacher at a local school, had a nice selection of the St. Clair fern fossils. He had a few large specimens on which white arrows pointed to and identified each type of fossil, because he used to take them to schools for presentations. I wanted Andy to have some good specimens of his hometown fossils, so after a brief negotiation, those beautiful specimens came back with us. They are still part of our collection. The largest one is 2 feet, 5 inches across and 17 inches tall, with visible fossils on the both sides.
One of the most commonly found fern in the fossils from St. Clair is Pecopteris, an extinct genus of seed fern.
All these plant fossils occur in the Llewellyn Formation. The plants died and fell into the swamp, and because of the environment’s low temperature, pressure and oxygen conditions, the plant tissue was slowly replaced by pyrite from sulfides. It is believed that the whitish mineral coating, an aluminum silicate called pyrophyllite, replaced the pyrite at a later stage, as the sediments piled up and the temperature and pressure became greater. In some instances, there is a yellow coating. The black shale matrix can easily be split, which may reveal fossils of better quality or different types that were hiding inside.
Another fern most commonly found in the fossils from St. Clair belongs to the extinct genus of Alethopteris.
A fern is one of a group of vascular plants that reproduce via spores and have neither seeds nor flowers. Ferns first appeared in the fossil record about 360 million years ago (mya), and those from St. Clair date from around 300 mya.
The ferns most commonly found in the fossils from St. Clair are of the extinct genus of Alethopteris, the seed ferns Pecopteris and Neuropteris (and Neuropteris Ovata), and Sphenophyllum, with fossilized leaf whorls, which are arrangements of sepals, petals, leaves, stipules or branches that radiate from a single point (Common Fossils of Pennsylvania, Donald M. Hoskins, 1973, 1999, 2019). Also found are Cordaites, an extinct genus of leaf seed plants with long strap-like leaves with nearly parallel edges (318 to 299 mya).
All St. Clair fossil bed sites are owned by the Reading Anthracite Coal Company, and have now been fenced off. Any digging or surface collecting is strictly prohibited. Some local gem and mineral clubs have received permission to go in and collect. Please check with your local club. Also, please respect the privacy rules and keep safety in mind.
Two Pennsylvania museums have great fossil collections: the Carnegie Museum of Natural History, in Pittsburgh, and the State Museum of Pennsylvania, in Harrisburg. The Rutgers Geology Museum in New Brunswick, New Jersey, also has a fern fossil collection.
This article, with personal recollections, is a tribute to my husband’s hometown of St. Clair and his memories, heritage and family.
Helen Serras-Herman, a 2003 National Lapidary Hall of Fame inductee, is an acclaimed gem sculptor with over 39 years of experience in unique gem sculpture and jewelry art. See her work at www.gemartcenter.com and her business Facebook page at Gem Art Center/Helen Serras-Herman
All photos by Helen Serras-Herman
The Cover photo is a large specimen in our collection of St. Clair fern fossils measures 10 inches wide by 15 inches tall, and features Pecopteris, Neuropteris ovate, and Cordaites with long, strap-like leaves.
TGMS member David K. Joyce recently produced a new music video entitled "Diggin' in a Hole". The music video had its "world premiere" recently, as the kick-off to the Rochester Mineralogical Symposium, which was entirely on-line this year. It was a hit! The video features mineral collectors from many places in the world collecting minerals in many different spots in the world. There are a few TGMS members amongst the collectors in the video plus many other personalities from the world of mineral collecting, that you may recognize. We hope that you'll enjoy it! YouTube url: https://www.youtube.com/watch?v=8bHzn2poBKE&t=18s
TGMS was sent this great video link by a TGMS member and suggested that we post it on our website … so click on the link to watch a “future” mineral collector having fun opening his birthday present … enjoy!
FROM: Museo Minerales de Zacatecas . Jesús Salinas Estrada
BETTER MINERALS THAN VIDEO GAMES AND MOBILE.
My good friend Pedro Idirin told me that his grandson was caught in the eye of minerals and that he wanted to encourage that taste that he thought was better than a video game or a cell phone, so he asked me for a few minerals to give to him for his birthday and I was really happy to see how enthusiastically he receives his gift. Facebook url: Museo Minerales de Zacatecas . Jesús Salinas Estrada - MEJOR MINERALES QUE VIDEOJUEGOS Y MOVIL. | Facebook
Peter Megaw
2020 TGMS Special/Guest Exhibits Chair
We are very excited about our Theme for the 2020 Tucson Gem and Mineral Show ®: “World Class Minerals”… and we're expecting it to bring an outpouring of top-quality specimens from all over the world. However, we are getting a lot of questions about what World Class means, so here's a bit of an explanation. Before touching on all the physical aspects of World Class mineral collecting, we need to acknowledge the World Class Mineral Community to which we belong, composed of people passionately interested in minerals and sharing their knowledge, time and specimens with others. The TGMS Show relies on this community to annually volunteer their precious pieces to help us assemble a World Class Mineral Museum that exists for a mere four days and then vanishes, never to be seen in that form again. We try to pick themes that will stimulate exhibitors to use their imagination to determine how to play to the strength of their collections and hope that this freedom encourages them to have fun in deciding what they have to show off that fits the theme. Experience shows that our attendees appreciate the process...or at least the results. So, keep in mind this means that to a significant extent what is World Class is up to you because there is no single, unique yardstick for World Class...although like fine art most of us "know it when we see it"... and are often willing to discuss it endlessly. Show us...and the world...your best!!!
Merriam Webster defines World Class as "being of the highest caliber,” which sounds simple...but who makes the call and based on what? Mineral specimens are different from most other collectibles such as stamps, coins, comic books and baseball cards where the ideal is a known physical paradigm that each other example can be compared to. However, like fine art, each mineral specimen is unique, and appreciation is subjective on many levels; most mineral collectors use their experience and aesthetic sense to weigh their personal reactions to a Kongsberg silver versus an agate slice much as an art aficionado does with a Rembrandt versus a street-fair offering. What matters is what resonates with the individual, not what we think will resonate with an expert or group of experts. There may be consensus on what is aesthetic at a given time, but tastes change ... Renoir, Van Gogh and Picasso were not appreciated in their day … so show us what you think is the best and let fashion catch up when/if it does.
To many, World Class conjures up visions of highly valuable giant colorful gem or oxide crystals, and we wholeheartedly welcome exhibits of these! But it can also encompass a suite of specimens from a World Class locality like Tsumeb, Ojuela, Broken Hill or Franklin or superb wulfenites, sulfides, fluorites, quartz etc., from a single remarkable pocket or mine, or a range of localities. It can be a collection of nicely matched Thumbnails or Miniatures … or Micros (remember, many mineral species never get more than a few millimeters long, so the world's best may need a microscope for proper appreciation). The best specimens from a famous by-gone collector or author would clearly rate, as would the best specimens from your collection...after all they are the best in your world. In the final analysis it is YOUR perception that matters... specimen value, or species popularity need not (many might argue should not) be your guiding criteria!
Another avenue we want exhibitors to explore is how perceptions of what is World Class have evolved over time. Tastes change and many of the spectacular specimens available today, collected and prepared with exquisite care, reflect efforts to meet the demand from increasingly sophisticated collectors. This ties nicely into our celebrating the 50th Anniversary of The Mineralogical Record! Founded during the TGMS Show back in 1970, The Mineralogical Record (MR) has both documented the evolution of mineral appreciation and led the way by expanding awareness of what is out there and just how good, good can get (an integral aspect of World Class). The MR has spearheaded focus on appreciating the artistic aesthetics of mineral specimens; something that has more and more influence on TGMS exhibits and personal collections every year. The MR also strives to present the historical, cultural and geological context of the spectacular minerals in their features, enhancing our understanding of where the specimens come from and how they get to us. The MR's modest subscription price is within reach of almost all collectors and provides exposure to the best of what exists, regardless of whether or not we personally can possess it. Simultaneously the MR has raised the bar for mineral publications across the world and has led us to today's well written and profusely illustrated journals including Rocks and Minerals, Mineral Monographs, Mineral Up, Lapis, Mineralien Welt, Monde et Mineraux, Le Regne Mineral, Bocamina, Mineral Lover and Mineral Observer. Combined, these let all of us build World Class libraries of mineral literature of a quality that simply did not exist before The Mineralogical Record came along!
Peter Megaw
Special & Guest Exhibits Chair
Twenty-two members attended the May 11, 2019 TGMS Field Trip to the Cal-Portland Rillito Cement Quarry. Just off of Twin Peaks Road, a few miles west of I-10, the quarry produces the raw materials for Cal-Portland’s Portland Cement plant about five miles north of north of the quarry off I-10.
Quarry Manager, Jared Stokes graciously hosted us, describing the general geology of the deposit, the rock units mined for various grades of cement, and the process used to grind and mix the recipes to produce cement with different specifications. He also explained that we were standing in the hole created by the removal of one of the Twin Peaks, for which the Road and an Elementary School were named. Mining had begun there in the 1940s. Besides being a great host, Jared was very interested in any insights we could provide about the geology and mineralogy of the rocks.
The nature of cement quarrying requires very consistent rock properties and composition, which, in general, is not promising for a mineral collecting trip. Recognizing that, Jared took us to a portion of the quarry where the rock is much more variable, broken by numerous veins and intruded by igneous dikes. Prior to the trip, he had his equipment operators pull numerous piles of the various rock types out onto the bench, to make them more safely accessible. This and the fact that we were the only ones in the quarry that day, we were free to wear comfortable shade hats rather than hard hats. (As he pointed out in his safety lecture, the greatest hazard that day was the sun!)
Members collected a number of interesting specimens, including small water-clear calcite crystals with limonite-goethite inclusions, nice manganese dendrite specimens, a dense caliche-cemented breccia, and distinctly pink calcite vein pieces. Everyone drooled over a large boulder of the material, out of reach on the bench slope above us. A few small fluorite crystals were collected, but none of the banded fluorite collected on a previous trip.
One of the attached pictures shows pink calcite veins, crosscut by later white calcite. A second picture shows a spectacular manganese dendrite, more than two feet “tall”. While no-one probably found anything that will win a “best of show” trophy, it was an enjoyable and easy trip, made all the better by the nice weather and the gracious hospitality of Cal-Portland.
Article/photographs by Mark Marikos and Ron Gibbs
Saturday, October 13, 2018, TGMS held its second TGMS Family Fun Day.
Living in Arizona, a rainy day is usually something that we don’t worry about; actually, something we are delighted to see. But leading up to that Saturday, the TV weather announcer kept upping the percentage of rain. Most of the time they come close but this Saturday, they were right!! Once it started to rain it rained ALL DAY!!
Being rockhounds, we are all pretty much optimistic. Because when we go out collecting, we are sure that we are going to find something spectacular. But on this very rainy day, our optimism wasn’t that high … but of all the events that where going on in the City of Tucson that weekend … OURS was inside. That is like having an “ace in the hole.”
At 9:57 a.m. we had our first participants through the door … Danelle and Jaden Arturet. They braved the rainy weather and came to our TGMS Family Fun Day! Because Jaden was our first child (literally) through the door, she got to pick out a very special mineral specimen for herself … it was a really nice quartz crystal. Thank you both for coming!
Everyone through the door was greeted with a smile, then handed a “mineral passport” card, plus a raffle ticket (for hourly TGMS Membership giveaway). The “mineral passport” cards where stamped by each station that a child stopped and visited with. They had lots to see! The different stations were; fossils, micros, meteorites, rock and mineral identification, fluorescent mineral display, walk through a cave, rock dig, hourly giveaways, rock identification, a coloring contest, and personalize a bracelet.
After taking an earth science trip around the room, they got to go to the “spin the wheel and win a prize!” We had mineral specimens, hats, gold pans, 10x eye loops, lanyards, bags, and a host of other fun things to choose from. It was fun listening to hoots and hollers when the “wheel” landed on a “TGMS Gold Seal.” That’s when they got to choose their OWN very special mineral specimen.
We had over 250 people participate. There were parents, grandparents and children that came to visit us on that fun and rainy day. We feel that we had a pretty successful event. We received lots of “Thank You’s”, donations to the cause and we even sold a few TGMS products. By all accounts … it was a SUCCESS! AND we all had fun!
A big “THANK YOU” goes out to: Tim McClain, Ron Gibbs, Mark Ascher, Brad Gibbs, Victoria Fila, Rose Marques, Kerry Towe, Mike Hollonbeck, Diane Braswell, Mary Kirpes, Kent Stauffer, Linda Stauffer, Daniel Kirpes, Christine Marikos, Mark Marikos, Ortrud Schuh, Louis Pilll, Bob Melzer, Bill Shelton, Myles Isbell, Jennifer Isbell, Dick Gottfried, Linda Oliver, Bre Oliver, Trey Oliver, Kyleigh Oliver, Cailen Oliver, Molly Radwany, Beverly Lynch, Susanne Collier, Marilyn Reynolds, Bruce Kaufman, Warren Lazar, Cathy Logan, Pat McClain.
So onward and upward to our next community outreach program and, hopefully, we will do this very special event again!
Since 1946
A community committed to geology, mineralogy, lapidary and allied earth sciences, the Tucson Gem and Mineral Society, Inc. is a non-profit organization, established in 1946 by a small group interested in mineral knowledge and appreciation.
