Contributed Papers in Specimen Mineralogy
THE TWENTY-FOURTH TECHNICAL SESSION of the Rochester Mineralogical Symposium (RMS) was held on 13 April 2007. Twelve abstracts were accepted and presented as oral papers. The review panel consisted of Dr. Steven Chamberlain, New York State Museum; Dr. Carl Francis, Harvard Univeristy; Dr. Robert King, Tewkesbury, Great Britain; Dr. Marian Lupulescu, New York State Museum; and Dr. George Robinson, Michigan Technological University. PSEUDOBROOKITE FROM THE NINE MILE PLUTON, MARATHON COUNTY, WISCONSIN. T. W. Buchholz1, A. U. Falster2, and W. B. Simmons2. 11140 12th St. N., Wisconsin Rapids, WI 54494; 2Dept. of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148.
The Ladick Trucking and Excavating weathered granite quarry is located approximately 1 mile east of State Highway 107 in the southwest portion of the Proterozoic Nine Mile Pluton, the youngest and most silicic of four plutons comprising the Wausau Complex.
A limited amount of an alteration assemblage associated with a thin quartz-pyrite-fluorite vein was recovered from a pile of shot rock derived from blasting large boulders removed from the grus in the northern portion of the operation. The vein was emplaced in a fracture cutting the granite, and it appears fluids circulating along the fracture preferentially removed quartz and perhaps other minerals from adjacent granite to a distance of up to about 12 cm from the fracture. Subsequently, K-feldspar, biotite, minor quartz, and a series of associated minerals described below were deposited.
Pseudobrookite forms black to dark gray elongated crystals to approximately 1.5 mm in length, clustered in radiating sheaves or as single crystals. EMP analysis of clean grains shows no significant components other than Ti and Fe and minor amounts of Mn and Nb. Morphology is that of ideal, short prismatic pseudobrookite. Associated minerals other than K-feldspar, biotite, and quartz include ilmenite, rutile, anatase, sphalerite, chalcopyrite, pyrite, arsenopyrite or marcasite (now represented by goethite pseudomorphs), molybdenite, cassiterite, fluorapatite, fluorite, monazite, zircon, and a LREE-carbonate mineral, probably bastnasite- (Ce). Secondary minerals include small but attractive sprays of gypsum crystals; the Ca was probably derived from weathering fluorite and the S from weathering sulfides. Interestingly, the cassiterite crystals often contain inclusions of fluorapatite and monazite; all monazite identified so far has been as inclusions in cassiterite.
Although pseudobrookite typically is found in vugs in certain eruptive rocks, it appears that the Nine Mile pseudobrookite probably formed in an environment that was similar in at least some characteristics. As indicated by the association with cassiterite and molybdenite (first report for the Nine Mile granite), fluorite, and other Ti-bearing oxides, the conditions were probably high- temperature volatile-rich and Ti-rich. Conditions were likely close to a pneumatolytic environment-consistent in these respects with the typical pseudobrookite locality. No doubt the ambient pressure was somewhat higher, although it is believed that the Nine Mile granite was intruded at a shallow, albeit as yet undefined level in the crust. Hence, the environment of formation probably bore at least some strong similarities to the usual volatile-rich, high- temperature andesites and rhyolites that are the normal hosts for pseudobrookite.
GET READING! T. S. Ercit, Canadian Museum of Nature, Ottawa, Canada K1P 6P4; firstname.lastname@example.org.
Thanks to improvements in computer technology, it is possible for English-speaking people to obtain relatively good-quality translations of papers written in other languages. These two improvements are: better and cheaper flatbed scanners bundled with multilingual optical character-recognition (OCR) software, and the greater availability and functionality-and much lower cost-of modern translation software.
Using a common Hewlett-Packard HP4570c scanner (retail cost $160 US), and the translation software SYSTRAN (the Personal version of the global languages pack of twelve languages retails for $179 US), I have translated more than 150 papers in the last three years, most of which involve Russian or Chinese papers on granitic pegmatites. A less-expensive approach is to purchase a scanner and use the free online translation service at the Babel Fish site: http:// babelfish.altavista.digital.com/babelfish.
The zero-cost approach is to bypass scanners altogether by obtaining pdf versions of papers from authors, libraries, or the World Wide Web, and, of course, to use Babel Fish to do the translation.
The quality of scanners and OCR programs varies widely. OCR programs are by no means perfect; misinterpretations of characters or letters are not uncommon and can be difficult and time consuming to fix. Shortcomings of many OCR programs include: (1) The use of abbreviated character sets. For example, the OCR program currently in use in HP scanners does not recognize most Chinese characters for chemical elements-a real drawback for mineralogists, and it also does not recognize many older Japanese characters that, although no longer in use in modern Japanese, are quite common in papers pre- dating the early 1950s. (2) A lack of any measure of reliability, e.g., a color coding to indicate whether each character was interpreted unambiguously, approximately, or not at all.
If OCR programs are imperfect, then translation software is best described as a mere approximation. Due to variations in the rigidity or formality of different languages, and the different degrees of attention paid by software companies to translating between different sets of languages (including attention to scientific jargon), some pairs of languages give good translations, and others, horrible translations. SYSTRAN does a very good job of translating Russian to English, a fair job of translating Chinese and modern Japanese into English, but does a poor job translating many Indo- European languages into English (German to English is particularly bad). Nonetheless, it is now possible for nonreaders of Russian to get a very good understanding of Russian geology publications, and for nonreaders of Chinese and Japanese to get at least the gist of papers written in these languages. So, as the title says, get reading-there’s certainly no longer any excuse to overlook Eastern scientific literature!
WAYLANDITE, BISMUTH, AND ASSOCIATED MINERALS FROM THE WATERLOO QUARRY, SOUTHERN WISCONSIN. T. W. Buchholz1, A. U. Falster2, and W. B. Simmons2. 11140 12th St. N., Wisconsin Rapids, WI 54494; 2Dept. of Geology and Geophysics, University of New Orleans, New Orleans, LA 70148.
The Michels Materials Waterloo quarry exposes Baraboo Interval quartzites and metapelites that have been intruded by small pegmatites of Wolf River age, approximately 1,440 Ma (Aldrich 1959, cited in Brown 1986). The highly evolved pegmatites probably formed as a result of regionally widespread Wolf River-age magmatism (Medaris et al. 2003). Buchholz, Falster, and Simmons (2002) reported the presence of weathered pegmatites bearing gahnite, mangano-columbite, manganotantalite, and associated minerals, including lithian muscovite.
Since then, examination of better-preserved pegmatite material from the lower level has revealed an interesting suite of primary and secondary minerals. Buchholz, Falster, and Simmons (2005) reported bismutomicrolite, as grains to approximately 0.4 mm embedded in feldspar, and Bi secondary minerals, predominantly kettnerite and beyerite, as replacements of rodlike to acicular crystals of an unknown mineral. Lepidolite was also identified in the lower-level pegmatites.
More recently, native bismuth has been found as small irregular masses and tiny elongated to bladed crystals embedded in quartz and in small vugs. Kettnerite has also been found as small, thin, flaky crystals on waylandite. Waylandite occurrs as tiny well-formed crystals in small vugs, associated with kettnerite and rodlike crystals of bismuth. Uranmicrolite and microlite have both been found as small yellow-brown masses in quartz. Spessartine is locally abundant in the lower-level pegmatites and is essentially Ca free. Other associated minerals include apatite, manganocolumbite, manganotantalite, thorite, and hafnium-rich zircons.
The highly weathered upper-level pegmatites locally contain acicular crystals of a metallic mineral along surfaces of quartz grains and embedded in kaolin. The crystals are frequently partially to completely altered to kettnerite and other Bi secondary minerals and appear to be bismuth plus/minus secondary alteration products. The persistence of native bismuth in this highly weathered zone is puzzling. It is tempting to speculate that circulating MVT-related (Mississippi Valley-type) fluids during Paleozoic burial penetrated this weathered and permeable zone, remobilized residual Bi secondary minerals, and reprecipitated the Bi as native Bi. MVT- mineralization is present in overlying sediments as abundant goethite replacements of pyrite and marcasite. It is hoped that further operations in the lower level will continue to expose relatively fresh material and allow a better understanding of these interesting pegmatites and their associated mineralization. REFERENCES
Brown, B. A. 1986. Baraboo Interval in Wisconsin. In Proterozoic Baraboo Interval in Wisconsin. Geoscience Wisconsin 10:1-14.
Buchholz, T. W., A. U. Falster, and W. B. Simmons. 2002. The Waterloo quarry: A new locality for gahnite, manganocolumbite, and manganotantalite in southern Wisconsin. Rocks & Minerals 78:118.
Buchholz, T. W., A. U. Falster, and W. B. Simmons. 2005. Mineralogy of pegmatites and spatially associated metasomatized zones, Michels Materials quarry, Waterloo, WI. Proceedings and abstracts, 51st Annual Meeting-Institute on Lake Superior Geology, part I:8-9.
Medaris Jr., L. G., B. S. Singer, R. H. Dott Jr., A. Naymark, C. M. Johnson, and R. C. Schott. 2003. Late Paleoproterozoic climate, tectonics, and metamorphism in the southern Lake Superior region and Proto-North America: Evidence from Baraboo Interval quartzites. Journal of Geology 111:243-57.
MUSHROOM TOURMALINE AND ASSOCIATED MINERALS FROM PEGMATITES NEAR MOMEIK, MOGOK STONE TRACT, MYANMAR (BURMA). A. U. Falster1, A. Peretti2, and W. B. Simmons1. 1Dept. of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148; 2GRS Gemresearch Swisslab AG, Hirschmattstr. 6, PO Box 4028, CH-6003 Lucerne, Switzerland.
Tourmaline in a fantastic mushroom-shaped morphology has been produced from Myanmar since the 1800s. Pegmatites in the vicinity of Momeik, north of Mogok, Myanmar, are the source of the pegmatites producing the peculiar mushroom-shaped tourmalines. These LCT-type (Li-Cs-Ta-enriched) pegmatites occur in a belt of evolved tin- tungsten S-type granites and their pegmatites. This 1,500-kilometer- long belt stretches north-south through Myanmar. The pegmatites are generally modest in size, 1-5 meters thick, and up to 300 meters long. Mining operations are mostly small.
The majority of these mushroom-shaped tourmalines are pale pink, almost colorless, to intensely red. Commonly, the core is dark, and occasionally thin bands of dark color occur in the pink parts of the crystals as well. Some of the tourmalines are of the typical prismatic morphology, whereas others show a diverging morphology, and still others form the most fantastic forms and intergrowths. The diverging crystals are only slightly offset from each other, but subsequent generations of offset subindividual crystals bring about more intense curvatures. More drastically offset crystallites would hinder their growth and would not be able to continue growth. The largest specimens of mushroom tourmaline weigh around 1 kilogram, but smaller sizes are more typical.
Electron microprobe analyses reveal compositions ranging from a dark and Ti-rich schorlitic core to a light-colored elbaitic overgrowth. A liddicoatite component is distinct in the pink portions but does not become dominant. Several samples consist of rossmanitic zones and, in some, an olenitic overgrowth as the final crystallization was observed.
Associated minerals in these pegmatites include the following species.
Quartz occurs in pale gray crystals.
Gray or white microcline in blocky crystals and white albitic plagioclase are rarely preserved, since feldspars have decomposed or are just not preserved for economic reasons.
High-fluorine topaz is abundant and forms fine crystals that may reach a mass of 1 kilogram.
Beryl (goshenite, aquamarine, and morganite) occurs. The morganite is alkali-element enriched.
Etched pollucite from miarolitic cavities occurs in centimeter- sized crystal remnants. The samples studied are true pollucite and not just cesian analcime, which is more common in the pocket stage in other districts.
Danburite occurs abundantly in some miarolitic cavities in crystals to several centimeters in length and has essentially ideal composition and very little chemical sustitution. Most crystals are colorless or yellowish in hue.
Columbite-group species are rare, and the only sample noted was a manganocolumbite. One small cluster of stibitantalite crystals to 3 mm in length has been noted as well.
Phenakite forms dominantly prismatic and mostly twinned crystals to several centimeters in length. Compositionally, phenakite shows no noticeable substitution.
Almandine-spessartine, biotite, magnetite, lepidolite, hubnerite- ferberite, and cassiterite have been reported, but no samples were available for this study.
Overall, the paragenesis bears considerable similarity to high-B and high-Cs pegmatites, such as the Malkhansk district in Siberia and the central Madagascar 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 40:647-62.
THE CRYSTALLOGRAPHY AND MINERALOGY COURSE NOTEBOOK OF DR. HARVEY W. WILEY. E. Grundel, 2000 S. 2nd St., Apt. 8, Arlington, VA 22204.
Harvey W. Wiley, LLD, MD, PhD (1844-1930), is best known for his central role in securing the passage of the 1906 Pure Food and Drug Act, a universally recognized landmark in public health legislation (Grundel 2002). Although he already had his MD degree, Wiley enrolled as a special student during the 1872-73 academic year in the Lawrence Scientific School of Harvard College, Cambridge, Massachusetts.
His main interest was chemistry, especially analytical chemistry. Among the courses he took was one in crystallography and mineralogy. The notebook from that course survives and has been examined (Wiley n.d.). The cover of the book lists the lecturer as Professor Cooke. Josiah Parsons Cooke Jr. (1827-94) was Erving Professor of Chemistry and Mineralogy (Conklin n.d.). He is considered the founder of the modern Department of Chemistry at Harvard. Analytical chemistry and mineralogy were intimately intertwined sciences even at this time, hence the dual subjects in Cooke’s title.
The content of the notebook gives a rare insight into what was taught in the United States during the nineteenth century in a college course in crystallography and mineralogy. Overall, the notebook’s content would look familiar to a student today. The crystallography section deals with the crystal systems, but there is little mention of symmetry properties. The mineralogy section deals with specific mineral species, mostly common minerals. A separate notebook from another (chemistry?) course contains a section on the analysis of calcite.
Wiley’s notebook, though not particularly remarkable, is a fine piece of nineteenth-century American mineralogical history.
Grundel, E. 2002. Harvey W. Wiley (1844-1930). Matrix 10:38-41.
Wiley, H. W. Personal papers, Box 185. Manuscript Division, Library of Congress, Washington, DC.
Conklin, L. H. Web site: http://www.lhconklin.com/bio/publica tions/harvard.htm.
A REEVALUATION OF NB-TA-TI OXIDES FROM THE RARE METALS MINE, MOJAVE COUNTY PEGMATITE DISTRICT, NORTHWESTERN ARIZONA. S. L. Hanson1, W. B. Simmons2, and A. U. Falster2. 1Earth Science Dept., Adrian College, Adrian, MI 49221; 2Dept. of Geology and Geophysics, University of New Orleans, New Orleans, LA 70148.
The Rare Metals mine is located in the Aquarius Range, approximately 40 miles southeast of Kingman, Arizona, in the Mohave County pegmatite district. This pegmatite was first investigated in 1955 and reported on by Heinrich (1960). His report gives pegmatite dimensions of approximately 600 feet in length, 40 feet in maximum thickness, a strike of N. 85 E., and a dip of 30-40 NE. It is a zoned, NYF pegmatite with a wall zone (quartz, feldspar, muscovite, and garnet), intermediate zone (quartz and feldspar), and quartz core. Marginal to both sides of the core are muscovite pods and scattered beryl crystals. Rare-earth minerals reported occurring in a fine-grained “line rock” on the footwall side of the quartz core include monazite, gadolinite, euxenite, yttrotantalite, and fergusonite.
A reinvestigation of pegmatites in this district has, to date, failed to locate the Rare Metals mine. For this reason, research samples from the original Heinrich study were purchased from Tony Nikisher during the 2005 Rochester Mineralogical Symposium and analyzed using electron microprobe (EPMA) and X-ray diffraction (XRD) techniques. EPMA results were evaluated using the statistical approach of Ercit (2005) and are shown in the figure.
Sample 820, originally labeled euxenite, lies in the euxenite and aeschynite field. An average of three EPMA analyses yields the following formula: (REE+Y0.305Ca0.152Ti0.135Si0.060 Th0.054U0.045Al0.024Mn0.012Fe2+0.012Pb0.007)O0.806(Nb0.771Ta0.698 Ti0.531)O2O4.
This sample has REE+Y dominant at the A-site, with Y as the dominant REE, and Nb dominant at the B-site. XRD analysis of a heated sample suggests a euxenite structure, thus the sample is euxenite-(Y). Low totals due to the presence of water, vacancies in the A-site, and higher Ca values all suggest that this sample is substantially altered.
Sample 825 was labeled yttrotantalite yet lies in the euxenite and aeschynite field of Ercit (2005). An EPMA analysis of the most homogeneous sample yields the following formula: (REE+Y0.844Ca0.052Fe2+0.05Th0.013Mn0.007Si0.007Pb0.005Al0.005 U0.002)O0.985(Ti0.859Nb0.833Ta0.308)O2O4.
This sample has REE+Y dominant at the A-site, with Y as the dominant REE and Ti dominant at the B-site; thus it is polycrase- (Y). XRD analysis confirms the euxenite-type structure for this mineral and reveals the presence of betafite. This, coupled with the variable Ti in the EPMA analyses, suggests that this sample is an intergrowth of polycrase-(Y) and betafite. Varying degrees of alteration characterize the sample. Sample 826 was originally labeled euxenite. Oxides from this sample are altered, inhomogenous, and composed of a highly altered intergrowth of betafite and fergusonite(?). The inhomogeneous nature of the sample precludes an accurate identification. Monazite-(Ce) was also identified in this sample. The late-stage Ti-enrichment indicated by abundant Ti in the oxide phases from this pegmatite is consistent with that seen in other Mojave pegmatite district pegmatites that host polycrase-(Y), Tirich euxenite-(Y), and ilmenorutile.
Ercit, T. S. 2005. Identification and alteration trends of granite-pegmatite-hosted (Y,REE,U,Th)-(Nb,Ta,Ti) oxide minerals: A statistical approach. Canadian Mineralogist 43:1291-1303.
Heinrich, E. W. 1960. Some rare-earth mineral deposits in Mohave County, Arizona. Arizona Bureau of Mines publication 167.
THE MINERALS OF CEDAR MOUNTAIN QUARRY, MITCHELL, VIRGINIA. L. E. Kearns1, R. N. Jenkins1, and D. Lipscomb2. 1Dept. of Geology and Environmental Science, James Madison University, Harrisonburg, VA 22807; 284 Pottery Ln., Faber, VA 22938.
Cedar Mountain quarry is located on a 1,000-acre tract in Culpeper County, Virginia, near the town of Mitchell. Upper Triassic to lower Jurassic-age diabase is quarried for dimension stone and gravel. The quarry originally opened in 1979, operating under the name of the A. H. Smith quarry. The A. H. Smith quarry became the Cedar Mountain Stone quarry in January 1994. In early spring 1998, mining operations in the quarry exposed several areas of extraordinary mineralization, which produced one of the largest prehnite specimens ever found in the state of Virginia. Sixteen different mineral species have been identified from the quarry.
There are two major styles of mineralization at Cedar Mountain quarry. The earliest resulted in an Alpine veinlike mineral assemblage (amphibole, epidote, titanite, and feldspar) that was later followed by a classic trap-rock/zeolite assemblage (prehnite, pectolite, apophyllite, stilbite, stellerite, and chabazite). Veins and fractures as well as irregularly shaped replacement areas within the diabase were mineralized by hydrothermal fluids immediately following the igneous emplacement of the diabase sheets.
A MINERAL’S FATE: SIXTY YEARS A PYROXENE AND NOW AN AMPHIBOLE. M. Lupulescu1 and W. Selden2. 1New York State Museum, Research and Collections, 3140 CEC, Albany, NY 12230; 2Rutgers University Geology Museum, New Brunswick, NJ 08901.
Once upon a time, in the early nineteenth century, Dr. Horton collected a “black, often with brownish tarnish” mineral from a quartz vein in the town of Cornwall, Orange County, New York. He sent the material to Dr. Beck who described it in 1842 as “exhibiting one very perfect cleavage like some varieties of pyroxene.” Beck analyzed the mineral and wrote that “it resembles hornblende, or still more arfvedsonite in its appearance,” and he considered it a new species, naming it hudsonite in “allusion to the river in the vicinity of which it occurs.” Dana (1844) listed hudsonite as a pyroxene but with “no record of further examination of it” (Weidman 1903), a classification that was accepted by Beck. Later, Brewer in 1850 and Smith and Brush in 1853 re-analyzed Beck’s original mineral. The latter authors made a more complete analysis and found 1.95 percent water by ignition, indicating that the mineral was an amphibole, not a pyroxene. Unfortunately, no later chemical analyses or optical properties were reported, and the mineral remained in the pyroxene group. Adams and Harrington described a similar mineral in 1896 from Dungannon Township, Hastings County, Ontario, Canada, and named it hastingsite. In 1903 Weidman re-investigated the material analyzed originally by Beck and compared the results with those of Adams and Harrington. The results were very similar, and Weidman realized that hudsonite is in fact hastingsite. In 1978 hastingsite was defined by Leake who recommended the name hudsonite be dropped.
Beck, L. C. 1842. Mineralogy of New York. Albany, NY: W. and A. White and J. Visscher.
Weidman, S. 1903. Note on the amphibole hudsonite previously called a pyroxene. American Journal of Science, 4th ser., 15:227- 32.
THE CICERO CLAY PITS: A TRUE MICROMOUNT MINERAL LOCALITY IN CENTRAL NEW YORK. M. V. Lupulescu, M. Hawkins, and S. C. Chamberlain, Center for Mineralogy, New York State Museum, 3140 CEC, Albany, NY 12230.
The Cicero clay pits, now built over, are just west of South Bay Road and south of Gillette Road at their intersection southeast of the Village of Cicero, Onondaga County, New York. The clay pits contain calcareous concretions to 10 cm that appear to have weathered free, probably from the underlying Lockport Dolostone. Cavities in these concretions are richly mineralized with a variety of mineral species, all of which are small enough to require high magnification for meaningful observation (i.e., the specimens are micromounts). This locality was exploited by local collectors from the 1960s until the site was subdivided and houses were built. It has, however, never been described in the literature. Much of our study was based on a comprehensive suite of specimens preserved in the Don Briggs micromount collection.
Barite occurs as prismatic colorless to white crystals consisting of two orthorhombic prisms and lateral pina-coids. Calcite is found in at least three distinct crystal habits including nearly acicular crystals, scalenohedral crystals, and distorted rhombohedra. The crystals range from colorless to white to a transparent amber color. Goethite occurs as single acicular crystals, flattened radial aggregates of acicular crystals, and hemispheres of acicular crystals. Rarely, thicker prismatic crystals are encountered. Both marcasite and pyrite are sometimes altered in part to goethite. Gypsum occurs as bladed, elongated, colorless prisms. Marcasite occurs as tabular and prismatic crystals, twinned crystals, and complex groups of crystals, sometimes with a reticulated appearance. Melanterite is found as sprays of minute, acicular, white crystals. Pyrite occurs as octahedral crystals and groups of crystals and as minute golden to brownish spheres. Sphalerite is found in groups of crystals that can be yellow, orange, or brown. All these minerals appear to have formed from low-temperature solutions.
Although large specimens sometimes show instability from the decay of iron sulfides in the matrix, mounted specimens from the crystallized cavities appear to be completely stable. The Briggs micromounts were collected more than thirty years ago and show no signs of instability.
CRYSTALLOGRAPHY AND HABIT OF HUANZALA-STYLE PYRITE FROM PERU. R. L. Morgan1 and V. King2. 11851 E. Main St., Rochester, NY 14609, email@example.com; 2PO Box 90888, Rochester, NY 14609, firstname.lastname@example.org.
The silver mining district at Huanzala, Huanaco Department, Peru, has been known during the last three decades as an important mineral specimen-producing area, perhaps currently producing more commercially available specimens than any other locality in the world. Huanzala pyrite is crystallographically complex, and otherwise relatively rare faces are commonly visible in hand-sized specimens. A long-term systematic search by the senior author has been made to acquire Huanzala pyrite for crystallographic study using laser goniometrical techniques. It should be noted that because of the abundance of pyrite specimens from Peruvian mines, many unlabeled specimens that have appeared in the marketplace as being from Huanzala are misattributed and are really from localities outside of the Huanzala area. We have been careful to verify the district origins of the specimens studied, and many shipments of known Huanzala origin have been examined.
Laser goniometry is particularly amenable to measuring large crystals, including crystals in clusters or attached to matrix. From a series of investigations, the following forms have been identified on Huanzala pyrite: cube a, rhombic dodecahedron d, octahedron o, and positive pyritohedra or pentagonal dodecahedra e, a, a, and [eth]; negative pyritohedra f and g; trapezohedra n and m; diploids s and x; and trisoctahedra p and q.
The simple trapezohedron is relatively uncommon worldwide, and seems to be more frequent. The various habits of Huanzala pyrite are frequently rich in the above-measured faces, and simple crystals are uncommon from the district. Major observed habits- including pyritohedral (common), octahedral (common), and cubic (uncommon)-typically have five or more forms present, crystals with one form only are almost unknown, and crystals with two forms are scarce. Some forms appear mutually exclusive, and no crystals contain all of the measured forms. Additional forms are present that are so etched on the crystals we observed that they do not yield satisfactory reflections for measurement.
BENYACARITE: NEW DATA FROM THE HAGENDORF-SUD PEGMATITE, EASTERN BAVARIA, GERMANY. M. L. Robbins1, A. U. Falster1, W. B. Simmons1, and S. Stark2. 1Dept. of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148; 2Barbarastr. 20, 92729 Weiherhammer, Germany.
The Hagendorf-Sud pegmatite is one of two quartz-feldspar pegmatite deposits located in the eastern portion of the Bavarian basement complex (Forster 1974; Strunz 1974). The Hagendorf-Sud pegmatite is a zoned, feldspar-rich, columbite-phosphate-type pegmatite with a quartz core and is related to the Variscan granites of the metamorphic Moldanubian gneisses. From 1906 through the mid- 1970s, Hagendorf-Sud was mined extensively for quartz and feldspar, with almost a million tons of feldspar mined previous to 1974. In the early to mid-1950s, about 6,000 tons of triphylite were mined for the Li content. Moreover, the abundance of phosphate minerals is the reason Hagendorf-Sud is widely known. Mucke (1981) stated that there are rockbridgeite-bearing and rockbridgeite-free parageneses and subparageneses for the various phosphate suites. Both the primary and secondary phosphate suites have been studied and noted throughout the years, though certain species and paragenses have been studied more thoroughly. Minerals found since the 1980s include, but are not limited to, schoonerite, leucophosphate, robertsite, whitmoreite, keckite, bermanite, pachnolite, carlhintzeite, switzerite, lipscombite, connellite, bassetite, morinite, and paravauxite (Mucke 1981). Benyacarite, ideal formula (H2O,K,Na)2Ti (Mn,V,Fe2+,Mg)2(Fe3+,Ti,Al)2(PO4)4(O,F)214H2O, is a rare secondary Ti-bearing phosphate found at Hagendorf-Sud that we analyzed in this study. Ternary plots based on electron microprobe analyses (EMPA) show variations in the X- and Y-sites. Analyses show Fe2+ to be dominant over Mn for several spot analyses. The following empirical formula is representative and indicative of a new species: (H2O)1.641 K0.344Na0.015)2Ti1.0(Fe2+1.244Mn0.78Mg0.003Ca0.013Zn0.006)2.056
3+1.11Ti0.631Al0.268)2.010[(PO4)4.026Si4+0.026)]4.052(O1.379F0.621)2 13.359 H2O. In addition, high Ti content in the Y-site was also found, ((H2O)1.552K0.431Na0.017)2Ti1.0(Mn1.096Fe2+0.909Mg0.00
n0.003)2.015(Fe3+0.786Ti0.894Al0.311)1.992[(PO4)4.009Si4+0.008]4.017 (O1.424F0.576)213.448H2O, as well as a composition with dominant Fe2+ in the X-site and Ti dominant in the Y-site, ((H2O)1.670K0.320Na0.010)2Ti1.0(Fe2+1.146Mn0.796Mg0.079Ca0.007
3)2.030(Ti1.008Fe3+0.907Al0.164)2.079[(PO4)3.9Si4+0.033]3.933(O1.266 F0.734)213.33H2O. True benyacarite was also found, ((H2O)1.578 K0.407Na0.015)2Ti1.0(Mn1.53Fe2+0.442Mg0.008Ca0.007Zn0.005)1.992 (Fe3+1.161 Ti0.653Al0.233)2.047(PO4)4.032(O1.414F0.586)213.422H2O. Formulas were calculated based on 18 anions. Fe2+ was used to fill the X-site, and excess iron was converted to Fe3+ and put in the Y- site. Oxygen and water content were calculated by stoichiometry. New data such as these breathe new life into a closed location!
Forster, A. 1974. Fluorite deposits and pegmatites in Eastern Bavaria: Part 2-The pegmatites in the area of Pleystein-Hagendorf/ North Eastern Bavaria. Fortschritte der Mineralogie 52:89-99.
Mucke, A. 1981. The parageneses of the phosphate minerals of the Hagendorf pegmatite: A general view. Chemie der Erde: Beitrage zur chemischen Mineralogie, Petrographie und Geologie 40:217-34.
Strunz, H. 1974. Granites and pegmatites in eastern Bavaria. Fortschritte der Mineralogie 52:1-32.
MINERALOGY OF HYDROTHERMAL FERRUGINOUS CLAY ASSOCIATED WITH COLORLESS AEGIRINE AND BITUMEN IN AN ALTERED PEGMATITE POCKET FROM MONT SAINT-HILAIRE, QUEBEC, CANADA. N. Zulinski and A. E. Lalonde. Dept. of Earth Sciences, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
We describe the occurrence of an assemblage of ferruginous clay minerals in specimen MOC1522 of the mineral occurrence collection of the Canadian Museum of Nature. The assemblage of clay minerals includes an Fe-rich chlorite species (chamosite) and hydrobiotite. The clay minerals occur as platy foliated pseudomorphs that are approximately 1 cm across and likely result from the replacement of primary mica crystals. The clay minerals are associated with nearly colorless, pale gray, or greenish-gray aegirine, microcline, pyrite, and siderite in a soft and friable porous rock that is presumably from an extensively altered pegmatite pocket. The clay mineral assemblage was analyzed by a series of powder X-ray diffractograms of specimens that were air-dried at room temperature, oven-dried at 100[degrees]C, collapsed at 500[degrees]C, and solvated with ethylene glycol. The diffractogram of the air-dried specimen reveals the characteristic 14.3, 7.2, 4.8, and 3.6 A peaks of a chlorite- group mineral but, in addition, shows a broad peak centered at 12.3 A. Glycol solvation did not produce any shift of this 12.3 A peak, eliminating the presence of a significant smectite-group component in the mixture and suggesting instead a mixed-layer clay composed of biotite and vermiculite (i.e., hydrobiotite). The presence of kaolinite or other 1:1 layer silicates (e.g., berthierine) in the mixture was ruled out by infrared spectrophotometry. Electron microprobe analyses of the clay mixture yielded elevated total FeO contents of 26.7-30.8 weight percent and very low MgO contents (1.3- 1.7 weight percent), suggesting that the primary mineral was annite. The clay pseudomorphs are associated with small euhedral needles of aegirine that were analyzed by powder diffraction and by electron microprobe analysis. The pale and nearly colorless nature of this aegirine is most bizarre. A thin black layer of lustrous and globular bitumen is found coating many of the surfaces of the platy pseudomorphs or cavities in the specimen. The material did not diffract X-rays, as expected and was shown by evolved-gas analyses to be composed primarily of carbon.
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