News Nuggets

Newsletter of the Albuquerque Gem & Mineral Club

President/Editor - Orlando Garcia; home phone: 345-0520; e-mail: jabog02@msn.com

VP-Programs - Grant Kuck; home phone: 323-1520

VP-Field Trips - Kimberly Richie; home phone: 296-8847

VP-Special Events - Hank Miller; home phone: 255-7218; e-mail: rgmhgm2@msn.net

VP-Field Trips - Ray DeMark; home phone: 822-8715; e-mail: RayDeMark@msn.com

Secretary/Historian - Dave Moats; home phone: 892-8163; e-mail: beepbeep59@hotmail.com

Treasurer - Stephanie Bell; Home phone: 281-7192; e-mail: stephbell22@yahoo.com

Editor - Darlene Nelson; Home phone: 271-4694; e-mail: agmcnews@aol.com

Show Chair - Paul Hlava; home phone: 255-5478; e-mail: hpf1@quest.net

Membership - Donna Scott; Home phone: 934-6564; e-mail: dutchessofalb@aol.com

Jr. Club - Carl Johnson; home phone: 344-3178

Nelson, Editor, 817 Sagebrush Trail, Albuquerque, NM 87123, or email to agmcnews@aol.com.

The Albuquerque Gem & Mineral Club was organized on January 22, 1944. The club is a non-profit organization dedicated to the advancement and enjoyment of the Earth Sciences and associated subjects. Its primary purpose is the exchange of information and the furtherance of knowledge of Mineralogy, Fossils, Geology, Rock Cutting and Gem Faceting and to stimulate interest in the development of these studies.

All Meetings are held at the NM Museum of Natural History, Albuquerque, NM. The general meeting is held on the 4^th Monday of the month (unless otherwise announced) at 7:30 p.m. The Junior Club meets at 6:45 p.m. prior to the general meeting. Board of Directors’ meetings are held at 7:30 pm on the first Monday of each month. (Call for location). The public is welcome to both meetings.

Visiting the home of the "Hope Diamond", seven of the world’s rarest known cut colored diamonds are on display – the first and only time they will be shown together.

Tonight’s meeting was held upstairs in the Museum’s I-Max Theater where we found excellent and adequate seating and viewing capabilities for the slides the 80 in attendance would be enjoying this evening.

Orlando announced that Walter Morris still needs material to tumble and polish for the soon to be State Fair that starts the second weekend in September. If you have material you would like to donate, please call Orlando or bring it to the next meeting as time is running short.

Hank will have sign-up sheets at next month’s meeting for us to volunteer our time sitting at the Club table at the Fair. There we hand out small bags of small mineral specimens to those interested and answer questions about our club. If you have any small specimens for this endeavor Orlando or Hank will also be glad and grateful to accept your donations. Anything left over will be used in next year’s show.

Ray briefed us about our next field trip that is to the famous Harding Mine. As an extra bonus he has arranged for us to camp overnight in the parking lot so that we can explore the dumps and area with the Club’s UV light. Ray has collected here and its environs for about 30 years and brought a large selection of about 30+ minerals for our examination tonight. He was able to show us the subtle color differences between lepidolite and rose muscovite found here along with some of the more unusual minerals you can expect to find. He had on display some beautifully polished lepidolite. He and Kimberly have tentatively set a date of July 26^th for the Club’s picnic at the San Pedro Mine. There the mine superintendent, Dr. Jerry Simmons, will lead us around the area and explain some of the area’s history and geology. If the last two years are any indication of attendance, we can expect a crowd, as it is a very popular collecting location.

Donna has name-tags for those who placed orders at $7/ea. and would like those who received one earlier and didn’t pay to do so immediately.

Dr. McLemore along with Dr. Nelia Dunbar did extensive research on spherulites in Rock Hound State Park, N.M. that ended about two years ago. Mr. Robert Colburn also did a lot of work on this subject that was acknowledged. He is the owner of the Geo-lapidary Museum you drive past, southeast of Deming, on the way to the Park and the person who has donated a significant collection of this local material to the Deming Luna Mimbres Museum collection on display in Deming. The only mining going on in the area is in the agate pits and sand & gravel pits.

The numerous spherulites at Rock Hound State Park are found in the 25 million year old rhyolite (high in silica and very viscous) obsidian layer that intruded Little Florida Mountains in the form of domes or dikes. These mountains are shield volcanoes composed of andesite of mid-Tertiary age.

The Thunder Eggs internal structure is controlled by crystallization dynamics and, it is speculated, takes days to weeks to form. Spherulites display distinct zoned structures with a core zone surrounded by a structureless zone then outer, darker zone, shell or rim. They also have many silica filled fractures and open-spaces that have been filled with silica. The outer shell zone has a very fine scale structure of concentric banding. Changing temperature and pressure forms the banding and crystals. Nelia Dunbar, using back-scattered electron imaging, an electron micro probe and qualitative X-ray analysis produced images and X-ray maps to show element distributions. She also did quantitative chemical analysis on the various zones. The observed patterns suggest that the Thunder Eggs formed during the cooling of the rhyolite. These tests showed bands of pure quartz intermixed with bands of intergrown feldspar and quartz and a little magnetite – the same chemistry as the lava from which the spherulites were formed. The transition between the outer section and the banded section shows a transition between rapid to slower growth of the crystals. The cores were composed of many fine-grained quartz and alkali feldspar crystals that show a texture. Many have cores of agate or quartz crystals.

There seems to be some stratigraphic control on the location of hollow vs. solid spherulites. In some hollow specimens the original solid form appears to have expanded from small, finely dispersed voids that might have been bubbles. It was explained that rhyolite has some water while quartz and feldspar have none. They speculate that when the magma begins to crystallize out the quartz and feldspar, the water comes out as gas bubbles. This water would be more than enough to account for the voids. Crystal growth rates and pressure are crucial combinations and may be controlling factors on generation or non-generation of large voids. If these bubbles combine and then pop they would form a large gas bubble or void while the magma was still plastic. Crystals would then form when silica-rich waters flowed through the void first depositing a rind of quartz. Rapid cooling of a silica saturated fluid allows a supersaturated solution to form that would precipitate chalcedony (cryptocrystalline silica). These supersaturated fluids are unstable and quickly deposit these layers of chalcedony, typically at lower temperatures (less than 220^oC). You need an initial supersaturated solution (several different processes can accomplish this) to get precipitation. We were shown Thunder Eggs that had been cut in half that showed spectacular "star" shaped interiors, a result of that popping of bubbles that is speculated formed this shape. These were found by Robert Colburn at the abandoned Sugar Bowl Mine.

The different colors are a result of other ions (Fe, Mn, Co, Cu), in minute, undetectable (by even an electron microprobe) quantities. After entering this solution they are deposited with the silica in the cyclic forming bands. One speculation is of fluids moving through microscopic pores in the rock by a process called "diffusion", eventually plugging up these pores and forming the outer rind. Multiple stages of different fluids come into the process. Concentrations of SiO₂ in water are highly dependent on temperature, pressure and salinity. Silica goes into solution as H₄SiO₄ and possibly as colloids. The solubility of quartz is not affected by PH until a PH=9. More than one stage of silica deposition is noticeable in the specimens that show a parallel banded layer of quartz contacting another banded layer of quartz resembling an angular unconformity. Mr. Robert Colburn has worked out a method of extracting specimens to study these relative angular positions and relate them to the tilting of the mountain/formation in which they were found. This requires the careful extraction and exact alignment of the specimen to make a cut perpendicular to the original alignment. He also discovered that in the Little Floridas the spherulites are found only in the obsidian layered deposits.

After questions were taken and answered concerning this very interesting presentation, we took a break for refreshments, bought door prize tickets and drew the winning numbers. We also had a further chance to add to our mineral collections, thanks to John Scully (and others?) that were giving away specimens of acicular jamesonite crystals, petrified wood and other minerals that had been collected at Santa Eulalia, Mx. and elsewhere.

Twenty-two AGMC members opted to stay late and camp out in order to search the dumps and outcrops for fluorescent minerals. UNM had positioned a port-o-potty near the mine portal, so facilities were available. Mike Potts brought the club’s short wave UV lamp and Tom Baker graciously loaned the club two long wave lamps to facilitate our search. Of course, some individual club members also had their own portable lamps. As it wasn’t going to be dark until around 9:00 p.m., most folks had their dinner and socialized while waiting for the sun o set. Scott Wilson provided a special treat for all by cooking a large peach/cherry cobbler in a camp oven. Thanks, Scott, it was great!

Apatite was the most abundant fluorescent mineral found throughout the mine. It fluoresces a very bright orange under short wave. A number of specimens of the rare eucryptite were also found and everybody was able to acquire at least one piece. Eucryptite is a rare lithium aluminum silicate that forms as an alteration produce of spodumene and fluoresces a begonia-rose under short wave. Some green fluorescing material was also found and it was determined to be hyaline opal. Spodumene fluoresces a cream color (best under long wave) and it was also very common on the dumps.

Fortunately, no one fell into a hole or broke anything while we were stumbling around the mine area. All in all, the trip seemed to be enjoyed by everyone who attended. Many thanks to Gilbert Griego, the caretaker, and the University of New Mexico for allowing us to visit the mine and stay overnight for fluorescent collecting. Most everybody was on their way home by 9:00 a.m. on Sunday – a fun trip!

I have developed the following over the years and thought I should share it with you folks. Please let me know if there are items missing or items that need more explanation so we can put the corrected version into the News Nuggets at a later date.

1 - Water for drinking. It might be to your advantage to bring your water in the frozen form so that you will have cold water.

2 - Something to wrap your more delicate treasures to protect them from damage (toilet paper, Kleenex, paper towels, paper napkins – newspapers are often too harsh on the "good stuff").

3 - Several containers to hold your findings - cargo trousers with numerous pockets and containers with several "pockets". Putting delicate specimens in large containers is not recommended as they may get damaged.

4 - Large plastic buckets. These are great for the large items that you do not want to break down in the field or those large items you want for your yard.

5 - There are several choices as to how to get the nice little specimen out of the ten pound rock. Some experts take little more than a rock hammer. Others.use the 3-4 pound sledge and an appropriate chisel. (See Item 2 under "At Home".

1 - Often, samples are available at the Club meeting prior to the field trip to give you an idea as to what to look for. If not there, it may be at the collecting area where you find our what you are seeking.

2 - There are several choices as to what you can bring home: mineral specimens, yard rocks, material for cutting and polishing, junkite (or a nicer term – "petrifact") – an unusual formation or pattern on a rock, fossils, or a combination of the above.

3 - The big deal is to go to mines where one can go underground. One time at this should be enough for most people, as the chances of getting extra special material is not great. Remember, all the material on the tailings piles was – at one time – in the mine.

4 - Unless you are a dealer, you should take only a reasonable amount of material, as you have to do something with it when you get home. OR, you can always use the excuse that you will be generous and let the members who could not make the trip have some specimens.

5 - Remember to wrap your delicate items in the paper you brought along.

2 – The Club has a rock trimmer (check it out from the Club president). It is good for specimens up to about ten pounds.

3 – Have Ray (or his designee) identify what you have. You may also take it to the Bureau of Geology and Mineral Resources in Socorro, where Dr. Lueth, the State Mineralogist, has his office. Be sure to phone first (505-835-5140) to make an appointment.

4 – Keep track of your treasures. I devised the "alpha-numeric system". The first digit is "A" for minerals beginning with "A". This is followed by three digits to accommodate 999 different "A" minerals. Then comes a dash and four more digits, so one can have 9,999 specimens of the same mineral. There is also the Dana system or numerous others, including writing the mineral name on the outside of a beer flat.

5 – The beer flat works very well for smaller items. They can be obtained from any liquor store. A store in Socorro places them in an outdoor trailer for anybody to take – free. I use the Althor plastic hinged beer flats. These are commercially available "beer type flats" of different sizes to accommodate larger specimens.

6 – The previously mentioned serial identification of specimens and the particular "beer flat" in which they are placed can be further kept track of using an available computer program.

You didn’t realize how complicated this business can be, did you? I presume that most of you will continue with the existing system you have used over the years. At my age, memory has gone by the wayside, and I need all the help I can get – even using the computer.

The HBO Meteorite, the largest single meteorite known in the world today, is on the HBO farm situated 25-km northeast of Otavi and near Grootfontein, in Namibia. When a meteorite enters the earth's atmosphere at an extremely high speed, the friction is so great that the meteorite burns up in the atmosphere and in the process produces a bright streak of light, which is readily visible at night and is commonly called a shooting star. A huge belt of such meteoritic material, the so-called asteroid belt, is present in the space between the planets Mars and Jupiter. Scientists have not yet reached agreement about the origin of these meteorites. It can, however, be stated that whatever falls into the earth from space is part of our solar system that developed some 4,600 billion years ago.

There are two main types of meteorites: iron meteorites and stony meteorites. Namibia is world-famous for its meteorites. The most extensive meteorite shower known is found in the southern part of the country and is called the Gibeon Meteorite Shower. It is estimated to have occurred over an area of 20,000 km. The more concentrated center of the shower extended over an area approximately 2,500 km in the vicinity of the village of Gibbon. The Hoba Meteorite was first described by Johannes Hermanus Brits in 1920 and was declared a national monument on 15 March 1955 with the permission of the landowner at the time, farmer Mr. O. Scheel. The meteorite weighs approximately 60 tonnes and measures 1.95 by 2.84 meters. Its thickness varies between 122 and 75 cm. The shallow pits and depression on the horizontal upper surface of the meteorite were caused by corrosion during its passage through the earth's atmosphere. Minor oxidation has occurred on the surface since. Due to the presence of a rare radioactive nickel isotope with a half-life of less than 80,000 years, scientists were able to determine that the Hoba Meteorite fell to earth less than 80,000 years ago. Analyses of age of the meteorite vary between 190 and 410 years.

The Hoba Meteorite consists of 82.4% iron, 16.4% nickel and 0.76% cobalt. Other elements present are traces of carbon, sulfur, and chromium, copper, zinc, gallium, germanium and iridium. Scientifically it is termed an ataxite, a meteorite with high nickel content. Under the microscope, material from the Hoba Meteorite displays the typical compact ataxitic structure with faint lines wedges and patches. The main minerals are kamacite (a nickel-iron alloy with 5-7% nickel) and taenite (a nickel-iron alloy with up to 65% nickel). High magnification shows intergrowth of the kamacite and taenite needles in the typical Wilmannstaetten structure. The meteorite also contains the more rare meteorite minerals schreibersite {(FeNi)₃P}, toilite (FeS) and daubreelite {FeCr₂S₄}.

The Hoba Meteorite is situated on the edge of the Kalahari plain that extends to the east and southeast. This plain is underlain by white calcrete of the Kalahari Group that fills the valley floors in the area. Underlying the calcrete are ancient granites as well as dolomites and limestones of the Otavi Group which also making up the surrounding hills. No crater or altered rocks have been found associated with the impact site. After the meteorite fell, a layer of calcrete gradually covered it. This calcrete was formed by the evaporation of near-surface groundwater, which carried calcium carbonate derived from the surrounding Otavi limestone. Today the region receives a maximum annual rainfall of only 175 mm and near the surface groundwater is less than abundant. The calcrete therefore suggests a more humid climate in the recent geological past.

Unfortunately vandals have damaged the meteorite. In 1985, Roessing Uranium Ltd. made funds available to the National Monuments Council to combat vandalism. In collaboration with Roessing, the council launched a project to protect the meteorite and make the surroundings more attractive for visitors. Mr. J. Angelbrecht, the landowner since 1987, donated an area for the development of the site. Subsequently, an information center was established to meet educational needs. The facilities were opened on 31 July 1987.

The biggest meteorite ever found on Earth is the Hoba meteorite. It weighed over 100 tons. This iron meteorite was found in Namibia, Africa. A lot of it has rusted away since it landed on Earth; it is still in its impact crater in Namibia.  The largest meteorite ever found in the United States is Willamette meteorite (named for the city in Oregon where it landed). This iron meteorite weighed fifteen tons and was found in 1902.

The meteorite consists of 82.4% iron, 16.4% nickel and 0.76% cobalt. The scientific classification of Hoba Meteorite is nickel-rich ataxite.

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