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Preparation for exam in GEOL 2224, Introduction to Mineralogy, University of Oklahoma - David London

Experimentally grown plumose mica - Dave London

Zonation in Rhodizite-Londonite from Madagascar - David London

Pegmatite Candy - Jeffrey E. Patterson

Euxenite from a NYF pegmatite, Western Australia - Mark Jacobson

Update on pegmatite material coming out of Brazil - David London

Hog Heaven - A PIG in Tucson (2003) - David London

Tourmaline Mushroom - Federico Pezzotta

Our first pig?... - Jeffrey Patterson

Amazin' Amazonite - David London

French Pegmatites - David London

 

Preparation for exam in GEOL 2224, Introduction to Mineralogy, University of Oklahoma

David London

Study area of University of Oklahoma's main Bizzell Library, in preparation for the final exam in GEOL 2224: "Introduction to Mineralogy".

With all of the discussion and effort going into new, non-traditional ways of teaching mineralogy, I thought I would share this with all who care.

I acknowledge that I am old-school in my thinking about what a university science course should be. Though I have adapted my course to address changes in the aptitude and preparation of today’s students, the course remains as challenging for the students taking it now as it was for better-prepared students twenty years ago.

I want my students to learn the principles of mineralogy, but more than that, I want them to learn how to learn, and thereby to elevate their academic effort (and, hopefully, reward). Students who are unwilling or unable to dedicate themselves to the necessary extent drop the course; about a quarter of them drop in each class. Each year, though, about a third of the students finally adopt my study recommendations and guides about half-way through the course. These include daily group study, reviewing and re-writing notes, comparing notes with other students, study cards (aka flash cards), and drills on the board from student to student.

The view here is of white boards in the student study section of our main university library. The content on the boards was written by one student in my mineralogy class, in preparation for the final exam. The student set out to write out everything he thought was important from the course, based on what he could remember, and then edited it as he referred back to his notes. It pleases me, and it should please others, to see students, like this one, who try to master the traditional content in traditional ways.

 

 

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Experimentally grown plumose mica

David London

Every now and then we grow a mineral texture that is as beautiful as it is complex and inexplicable. In this case, we grew plumose mica, starting with Fe-rich mica along its "spine" (brightest BSE signal), and radiating outward into muscovite. The mica spiral is almost entirely encased in a single quartz crystal, as are all micas grown from this series of experiments with the Macusani obsidian. The two together constitute a graphic intergrowth in the central melt pools of the experimental products. The mica cluster to the left of the spiral is probably connected to it, and both micas and quartz are surrounded by glass (quenched melt).

 

 

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Zonation in Rhodizite-Londonite from Madagascar

David London

Text + 3 pictures (pdf - 177 K)

Individual images

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Pegmatite Candy

Jeffrey E. Patterson (University of Calgary, Southern California Research Station) contributes this tantalizing photo of polychrome tourmaline crystals and the pocket they came from in the Himalaya mine, Mesa Grande, CA. The large crystal on the right measures 8 x 3 cm. The pocket, which was excavated by Jose Montes of Pala International, was located in 1998 by GPR imagery conducted and interpreted by Jeff. J.E. Patterson and J.D. Means have also posted a preliminary GPR survey of the Cryo Genie pegmatite (see PIG Articles), which can be accessed along with other Cryo Genie news at http://home.earthlink.net/~goke/GPR.htm.

 

 

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Euxenite from a NYF pegmatite

Western Australia

Beauty is in the eye of the beholder, and in addition to pink & blue tourmaline crystals the size of your arm, many PIGs will appreciate this photo from Mark Jacobson, presently in Western Australia. This very fine crystal of euxenite is from the Calcaling pegmatite, in a pegmatite field (newly recognized as NYF-type) named Mukinbudin, Western Australia. The euxenite crystal is 2 cm tall by 0.8 cm wide. It is hosted by albite and crystallized perpendicular to a flat ilmenite plate. Other accessory minerals from the pegmatite include ilmenorutile, monazite, fluorite, and beryl. Mukinbudin is within the Murchison Terrane of the Archaean Yilgarn Craton.

 

 

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Update on pegmatite material coming out of Brazil

For those of you who haven’t starting thinking about the upcoming Tucson Gem & Mineral Show, or if you haven’t been able to think of anything else for the past couple of weeks, here are some pegmatite-related photos from mineral dealer and collector Luiz Menezes (Luiz Menezes Minerals). Luiz graciously offered this update on pegmatite material coming out of Brazil. He regards the new find of kosnarite crystals to be most significant; the kosnarite crystals are sharp, up to 3 mm in size, on albite matrix associated with zanazziite, greifensteinite, rockbridgeite, ushkovite, goyazite, amblygonite, eosphorite, fluor-apatite, elbaite and lepidolite. They came from a pegmatite located on the Jenipapo district, Itinga, Minas Gerais, Brazil. Please note that this announcement is offered for information only, and it is not a particular endorsement of this or any other mineral vendor. — David London

Captions

Figure 1. Amblygonite crystal on albite, Telírio mine, Linópolis, Minas Gerais (3 x 3 cm)

Figure 2. Twinned manganotantalite, Alto de Furnas, Equador, Rio Grande do Norte (3.5 x 3.5 x 3.0 cm)(see Mineralogical Record, 33(6), 505-510, 521)

Figure 3. Twinned manganotantalite (3.0 x 2.5 x 1.2 cm ) on quartz, Alto de Furnas, Equador, Rio Grande do Norte (6 x 3 cm )

Figure 4. Twinned cassiterite (2 x 1.5 x 1.5 cm) on albite (5 x 5 cm), Divino das Laranjeiras, Minas Gerais

Figure 5. Gormanite (2.5 x 2.0 cm) on albite (5 x 5 cm), Linópolis, Minas Gerais

Figure 6. Kosnarite (3 mm crystals) on albite (4 x 3 cm), Jenipapo district, Itinga, Minas Gerais

Figure 7. Greifensteinite (based on preliminary EDS results) or zanazziite (ball-like aggregates, brown color) on greenish muscovite clusters; over the muscovite plates there are white ball-like aggregates of a mineral of the jahnsite-whiteite group (quantitative analyses in progress), Sapucaia pegmatite, Galiléia, Minas Gerais (type locality for frondelite, tavorite, moraesite, faheyite and barbosalite)

Figure 8. Beryllonite, contact twin (1.5 x 1.5 cm), Telírio mine, Linópolis, Minas Gerais

Figure 9. Twinned ferrotapiolite (5.5 x 4.0 x 3.0 cm), Sapucaia district, Divino das Laranjeiras, Minas Gerais.

Individual images

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Hog Heaven - A PIG in Tucson (2003)

Spectacular mineral specimens from granitic pegmatites are always available at the Tucson Gem & Mineral Show and satellite shows. This year seemed exceptional only because there was so much pegmatite material available in a wide range of prices. Pakistan and Afghanistan were well represented as usual, but Brazilian mineral specimens, in my opinion, were uncommonly good and plentiful, and new African material was available from a variety of sources. Rare pegmatite minerals, particularly phosphates, Nb-Ta oxides, and baestnesite, were offered by numerous dealers, and minerals of beryllium (beryl, phenakite, euclase, beryllonite, herderite) were everywhere. Even a PIG could go a lifetime without seeing pollucite, but some of the largest, most perfect crystals of pollucite ever found were offered by at least two vendors. If your tastes run more to the rock-forming minerals (and mine do), this was a great year for feldspars and micas. Here are some photos.. — David London

Captions

Figure 1. beryl v. aquamarine, 9.7 kg, found 1995 at Karur, Tamilnadu district, India; courtesy of K.C. Pandey, Superb Minerals India PVT Ltd

Figure 2. zoned beryl, v. morganite rim and aquamarine core, ~ 11 cm dia, Laghman province, Afghanistan; courtesy Kristalle/Crystal Classics

Figure 3. euclase, Last Hope mine, Miami, Zimbabwe; courtesy Kristalle/Crystal Classics (6 x 3 cm )

Figure 4. pollucite, Kandesh, Paprok, Kunar Province, Afghanistan; courtesy Victor Yount

Figure 5. pollucite, Kandesh, Paprok, Kunar Province, Afghanistan; courtesy Rob Lavinsky/Arkenstone

Figure 6. microcline, 20 cm tall, Aracuai district, Minas Gerais, Brazil

Figure 7. microcline, 45 cm wide, Aracuai district, Minas Gerais, Brazil

Figure 8. microcline with aegirine, 33 cm wide, Mt. Malosa, Malawi

Figure 9. albite with epidote, 12 cm wide, Capelinha, Minas Gerais, Brazil

Figure 10. zoned mica on microcline, 10 cm tall, Minas Gerais, Brazil

Figure 11. muscovite with garnet and beryl, ~ 35 cm wide, Pakistan; courtesy Haleem Khan/Hindukush Malala

Figure 12. muscovite street scene

Figure 13. beryl, topaz, tourmaline; courtesy Lucio Alvarez

Figure 14. tourmaline on quartz, ~ 40 cm tall, Minas Gerais, Brazil; courtesy Vasconcelos

Individual images

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Tourmaline Mushroom

On the subject of unusual habits for tourmaline (see PIG Comments & Questions), Federico Pezzotta submitted this photo of mineral collector Sarah Sudcovsky holding an exceptional mushroom-shaped tourmaline sample with minor quartz and feldspar. Bill Larson, who presently owns the specimen, reports the locality as Momeik, north of Mogok, Burmah. The Mogok Mineral Tract lies within a central belt of evolved tin-tungsten granites and associated topaz-bearing pegmatites that stretches north-south through the country (Zaw, 1998). Zaw (1998) summarizes the geology of the granitic rocks and provides a good petrologic and geochemical overview of the pegmatites.

Zaw, K. (1998) Geological evolution of selected granitic pegmatites in Myanmar (Burma): constraints from regional setting, lithology, and fluid-inclusion studies. International Geology Review, 40 (7), 647-662.

Captions

Figure 1. Tourmaline mushroom

Figure 2. Tourmaline mushroom detail

Individual images

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Our first pig?..

It has taken great restraint not to litter the PIG site with photos or other cute images of pigs (the four-legged kind: pigs, not PIGs). This photomicrograph from Jeffrey Patterson, however, is irresistible. The photomicrograph (cross-polars, 2.5 mm width) shows a quartz "pig" found in a sandstone that hosts pegmatites in Madagascar. The sample was collected by Jeffrey Patterson during the Madagascar pegmatite symposium in 2001 (see field guide by Federico Pezzotta in the PIG Articles).

Individual images

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Amazin' Amazonite

Weighing in at 105 kg, this amazonite crystal from Brazil (Fig. 1) was neither the biggest nor the best that Irene Ching of Bolva Group Inc. had to offer at Tucson 2004, but it was impressive enough. All the crystals from this particular locality (details not known or given) had a selective coating of black tourmaline on one face (Fig. 2). - David London

Individual images

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French Pegmatites

Dr. Jacques Patureau of Argentat, France, sent me these photos and brief text of pegmatite locations near the areas of Chabanne and Limousin, Central Massif, west of Clermont-Ferrand, France. The photos are striking, and the beauty and complexity of the textures were unexpected, at least by me. Dr. Patureau has graciously authorized me to post these photos on the PIG site, with brief captions. Any comments or questions can be addressed back to Dr. Patureau at patureau.jp@wanadoo.fr

. Pegmatite from Margnac, Limousin, Central Massive, France

This lenticular pegmatite was exploited for K-feldspar and piezoelectric smoky quartz crystals (up to 100 kilos). Common minerals: apatite, triplite, zwieselite, beryl, niobo-tantalite, autunite, torbernite. This zoned pegmatite with Be, Nb, Ta and Zr is embedded in an orthoclase leucogranite (granite with two micas) exhibiting a poorly marked alkaline trend of the Variscan chain (Carboniferous).

    Figure Margnac 1 represents a K-feldspar (perthitic microcline), rimmed by radial (curved) muscovite and then, on selected faces, radial platy albite (clevelandite), at the margin of the block microcline intermediate zone and the quartz core of the pegmatite. Quartz within the core reportedly contains hydrocarbon inclusions.

Pegmatite from Chabanne, Limousin, Central Massive, France

This more or less lenticular pegmatite was exploited for K-feldspar and beryl. Common minerals: beryl, apatite, triplite, topaze, amblygonite and turquoise, cassiterite, niobo-tantalite, autunite, torbernite. This potassic pegmatite with beryl is (locally) strongly albititic (Li, Ta, Nb are associated with albite) and exhibits a significant quartz core. It is embedded in a microcline leucogranite of Variscan age.

    Figure Chabanne 2 represents a contact between the granite and a pegmatite. The contact is denoted by zoned (layered) aplite.
    Figure Chabanne 3 represents a quartz core of grey to black colour in the centre and pinkish on the edges. The cracks of the quartz contain torbernite. These were the first uraniferous indicators found in the region (24,630 t of uranium were afterwards exploited from this region). The albitic portions contains amblygonite, niobo-tantalites, stannous tantalite, and topaz.

Individual images

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Figure Margnac 1

Figure Chabanne 2

Figure Chabanne 3

 


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