DOCSLIB.ORG

Mineralogy and Radiation Effects of Microlite from the Harding Pegmatite' Taos County, New Mexico

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mineralogy and Radiation Effects of Microlite from the Harding Pegmatite' Taos County, New Mexico American Mineralogist, Volume 71, pages 569-588, 1986 Mineralogy and radiation effects of microlite from the Harding pegmatite' Taos County, New Mexico G. R. LurvrpxrN.B. C. CnlxouMAKos" aNo R. C. EwINc Deparfinent of Geology, University of New Mexico, Albuquerque, New Mexico 87131 Ansrucr Microlite, rangrngfrom crystalline to metamict, is a principal accessoryin several lith- ologic units of the Harding pegmatite, Taos County, New Mexico. From the sequenceof lithologic units within the pegmatite,crystallization of microlite from the pegmatitemagma is inferred to have begun relatively late, after the formation of the beryl and quartz zones, and continued throughout the formation of the core zones and subsolidus replacement units. Over 200 chemical analysesof microlite determined by electron microprobe are reported, and they are consistent with the acceptedstructural formula, A2-^B2X6Y.-,' pHrO, where principally A : Ca, Na, IJ, Mn; B : Ta, Nb, Ti; X : O; and Y : F, OH, O. General featuresof microlite crystal chemistry identified include (l) a positive correlation between A-site vacanciesand the maximum Y-site vacancies,(2) a positive correlation betweenNa and F, and (3) a negativecorrelation betweenU and F. The latter is consistent with the interpretation that U at the A site in the pyrochlore structure is analogousto the uranyl group, UO3* , requiring O in place of F at the Y site. Microlite compositions from four of five lithologic units examinedare chemically distinct in terms of linear combinations of the variablesIJ, Fe, Ti, Bi, Ca, Ce, Pb, F, Mn, Ba, Sb, Th, Ta, and Na. The cleavelandite- unit microlites, the exception, not surprisingly have chemistries like those of the quartz- lath spodumenezone, which the cleavelanditeunit in part hasreplaced. The earliest-formed microlites from the quartz-lath spodumenezone have the highest Ta, Na, and F and are low in U and Mn. In contrast, microlites from the later microcline-spodumenezone and the replacement units are generally higher in Ti, Mn, and U and lower in F and Na. Chemical changesascribed to primary hydrothermal alteration from residual pegmatitic fluids include increasesin Ca, Mn, and Ti and an overall loss of A-site cations. Alteration effectsand chemical zoning within crystals, analyzedin terms of simple end members, ACaYO identifies the following principal substitution schemes:BNb- BTa,BTa- BNb, + ANaYF ANaYFand AEYE - aNaYF for core-to-rim zoning in crystals and ACaYO- and ACaYO- AEY! for primary alteration. Secondary (weathering) alteration results in de- creasesin Na, Ca, and F and increasesin HrO. The effectsof alpha-recoildamage due to the decayof constituent U have beenexamined. Becauseof the wide variation in U content (0.1-10 wto/oUOr), the microlites exhibit the full rangeof structural periodicity from completely crystalline (< I dpa), partially crystalline (up to lf20 dpa) to completely X-ray and electron diffraction amorphous (>20 dpa). Based on X-ray and electron ditrraction analysis, the progressivestructural modification of microlite udth increasingalpha dose involves (1) formation of isolated defect aggregates (i.e., individual alpha-recoil tracks) up through dosesof l0'4 alphas/mg with no detectable effect on the materials's ability to diffract X-rays or electrons,(2) continued damageand overlap of thesedefect aggregatesyielding coexistingregions of amorphous and crystalline domains at l0rs to 1016alphas/mg, and (3) complete amorphization at dosesgreater than 10'7alphas/mg. IxrnonucrroN tions have <10 molo/oTi and <25 molo/oNb (Lumpkin Minerals of the pyrochlore group (Fd3m, Z: 8) have and Ewing, 1985).Except for a single report of microlite the generalformula Ar-. B rXuY,-,'pHrO, whereA : Na, occurring in a granite (Sitnin and Bykova, 1962), most Ca, IJ, Pb, Sr, Th, REE, Bi, Sn2+,Ba, Mn, Fe2+;B: Ta, microlites are found in granitic pegmatites of the rare- Nb, Ti, h, Fe3+,Sna+, W; X : O; and Y : O, OH, F. element class(Grnj', 1982; Cernf and Burt, 1984). The Hogarth (1977) defined the microlite subgroup to have typical accessoryminerals associatedwith microlite in- Ta > Nb and Nb + Ta > 2Ti. Most natural composi- clude zircon, stibiotantalite, bismutotantalite, columbite- 0003-o04x/86/0304-0569$02.00 569 570 LUMPKIN ET AL.: MICROLITE FROM HARDING PEGMATITE tantalite, rynersonite, wodginite, and simpsonite (Von Ewing, I 976). Bedding (So)and transposition layering (So/ Knorring and Fadipe, l98l; Foord, 1982). S,) trend N8"E in Vadito rocks north of the pegmatite. Microlite was first described from the Harding peg- The primary foliation is slaty cleavageor schistosity (Sr) matite by Hirschi (1931), and during the period 1942- which trends Nl0'W and intersectsbedding at a low angle 1947 over I I tons were produced by hand-mining meth- (Holcombe and Callender, 1982).The pegmatitetruncates ods (Jahns and Ewing, 1976, 1977). The microlite con- So/S,and S, and must postdate F, and F, folding. centratesaveraged 68 wto/oTarO, and 7 wto/oNbrOr. The Severaltypes ofgranitic rocks are present in the area. first complete chemical analysescorrelated the changefrom On the basis of field evidence and limited radiometric light to dark color in five microlites with decreasingTal dating, Long (1974) considered the Harding and other Nb ratio and increasing OH/F ratio and the U, Ti, and pegmatitesto be late in the history ofgranitic magmatism. Mn content (Jahns and Ewing, 1976). Partial electron- He suggesteda separatemagmatic event for the pegmatites microprobe analyses(Suchomel, 1976) confirmed these 100 m.y. later than the youngest(unfoliated) granite and trends for Ta,/Nb, Ti, and Mn. Suchomeldid not analyze as much as 300-400 m.y. later than the oldest (foliated) for F and U, so the analysesdo not conform to the py- granitic rocks. Aldrich et al. (1958) determined K-Ar and rochlore structural formula (Chakoumakos, I 978). Rb-Sr agesof 1260 m.y. for lepidolite from the Harding Microlites are stable from ca. 500'C and 5 kbar down mine. RecentRb-Sr agesof 1336 + 73 for the "spotted to ambient, near-surfaceconditions and can accommo- rock" core unit,1264 + 128 for rose muscovite, and 1246 date a variety of rare elements as a function T, P, and + 40 m.y. for lepidolite were determined by Register(in melVfluid composition. Microlites from African localities Brookins el al., 1979). were broadly classifiedas primary, secondary,and uran- iferous types by Von Knorring and Fadipe (1981). They INrnnNx, zoNING AND REpLACEMENTuNrrs suggestedthat with time, microlites generally show de- The main pegmatite dike is characterizedby an asym- creasingamounts of Ta, Ca, and F with increasing con- metric sequenceof lithologic units from top to bottom. centrationsof Ti, U, Sb, Bi, Pb, and HrO. However, little These consist of six primary zones and two replacement is known about chemical variations in microlites within units. The following description has beencondensed from individual pegmatites(cf., Mih6lik, 1967; Foord,, 1976). Jahnsand Ewing (1976, 1977),Suchomel (1976), Chak- The abundanceof microlite in severallithologic units of oumakos(1978), and Norton (1983). the Harding pegmatite provides an excellent opportunity The hanging-wall portion of the pegmatite consists of to examine thesechemical trends. three primary zones.The continuous beryl zone includes Prior to this work, Suchomel(1976) noted higherNbrO, a thin, fine-grainedborder rind and coarser-grainedwall and lower TarO, contents in microlites from the micro- zonecomposed ofquartz, albite, and muscovite.Common cline-spodumenezone ("spotted rock") relative to those accessoryminerals are beryl, microcline, apatite, and co- from other units. Chakoumakos( I 978) made an extensive lumbite-tantalite. Below this is the quartz zone, a fairly petrographic and X-ray diftaction study of 30 located continuous unit of massive quartz with accessorymus- samples,three high-gradeore samples,and two analyzed, covite, microcline, and albite. The quartz zone is under- samples.No relationship between degreeof crystallinity lain by a spectacularquartz-lath spodumenezone char and lithologic unit was noted, implying that U does not acleized by spodumenecrystals up Io 2 m in length (see vary systematicallywithin the pegmatite. Most of Chak- Fig. 6, Jahns and Ewing, 1976). Microlite, beryl, apatite, oumakos' samples have been used in this study, along microcline, and lepidolite arecommon accassoryminerals with additional specimensdonated by Arthur Montgom- near the baseofthe discontinuous zone. The core ofthe ery. The purpose of this paper is threefold: (l) to discuss pegmatite in the western thick end is dominated by the generalfeatures of microlite crystal chemistry, (2) to ex- microcline-spodumenezone, otherwise known as "spotted amine relationships between composition and lithologic rock." Microcline, spodumene,and quartz are the major unit using statisticalanalysis, and (3) to describeradiation minerals with minor amounts of apatite, albite, microlite, effectsin microlites. and columbite-tantalite. Fine-grained lepidolite and Li- bearing muscovite commonly replace microcline and L,oc.c.rroN AND GENERALGEoLocy spodumene. Locally, the unit grades into nearly pure The Harding pegmatite is located in the Picuris Range massesof lepidolite. Two primary zones occur beneath l0 km eastofDixon and 30 km southwestofTaos in sec. the microcline-spodumenezone in the footwall portion 29, T23N, Rl lE. The pegmatite lies within Precambrian of the pegmatite.The perthite zoneis a discontinuousunit rocks of the Vadito Group. The main dike is about 370 of blocky,
Load more

Recommended publications
  • Maine the Way Life Should Be. Mineral Collecting
    MAINE The Way Life Should Be. Mineral Collecting The Maine Publicity Bureau, Inc. Quarries You May Visit # 1 Topsham: The Fisher Quarry is located off Route 24 in Topsham. This locale is best known for crystals of topaz, green microlite, and dark blue tourmaline. It has also produced other minerals such as beryl, uraninite and cassiterite. #2 Machiasport: At an area known as Jasper Beach there is an abundance of vari-colored jasper and/or rhyolite specimens. Located on Route 92. #3 Buckfield: The Bennett Quarry, located between Buckfield and Paris Hill, has produced fine specimens of blue and pink beryl including some gem material. It is also known for crystals of quartz, green tourmaline and rare minerals. #4 Casco: The Chute Prospect is best known for vesuvianite. It is located east of Route 302-35. Crystals of “cinnamon” garnet, quartz and pyrite are also found here. #5 Georgetown: The Consolidated Feldspar Quarry has produced excel­ lent specimens of gem citrine quartz, tourmaline and spodumene. Rose Quartz, cookeite and garnet are also found. #6 Paris: Mount Mica is world famous for tourmaline and this gem material was discovered here in 1821. This is one of the most likely places for a collector to find tourmaline. Mount Mica has produced a host of other minerals including beryl, cookeite, black tourmaline, colum- bite, lepidolite and garnet. (Currently being mined) #7 Greenwood: The Tamminen Quarry and the Harvard Quarry, both located near Route 219, have produced an interesting variety of miner­ als. The Tamminen Quarry is best known for pseudo-cubic quartz crystals, montmorillonite, spodumene and garnet.
    [Show full text]
  • Microlites and Associated Oxide Minerals from Naipa Pegmatites – Alto Ligonha – Zam- Bezia - Mozambique
    MICROLITES AND ASSOCIATED OXIDE MINERALS FROM NAIPA PEGMATITES – ALTO LIGONHA – ZAM- BEZIA - MOZAMBIQUE C. Leal Gomes, C.1 Dias, P.A.1 Guimarães, F.2 Castro, P.2 1 Universidade do Minho – CIG-R – Escola de Ciências – Gualtar - 4710-057 Braga, Portugal 2 LNEG – Rua da Amieira – 4465 S. Mamede de Infesta , Portugal Keywords: Alto Ligonha pegmatite district, LCT- pegmatite, U-Pb-Ba-Bi-Sb-microlite Naipa granitic pegmatites of LCT or a nuclear quartz+cleavelandite unit type, located in Alto Ligonha Pegmatite with miarolitic pockets. Pegmatites seem District, Monapo-Mocuba belt, Zambezia to be genetically related to Pan-African Pegmatite Province (Mozambique), biotite-amphibolic granites (zircon hosted are mined for tantalum and gemstones in lepidolite was dated 482±10 MA - U/ (topaz, OH-herderite; tourmaline and Pb). In the Northern Sector of Naipa mine, beryl). They are structurally complex, the internal zones are better defi ned, while concentrically zoned, intruding chlorite in the Southern domain, at least four and amphibole phyllites and gneisses. stages of hydrothermal alteration mask Internal units include wall zone (Mn- the primary structures in the outer and almandine line-rock), several intermediate inner intermediate zones. Two dilatation zones (K feldspar, albite, muscovite, episodes produced pegmatite veinlets, well spodumene) and a quartz±lepidolite core expressed in the Southern Sector (Fig.1). Estudos Geológicos v. 19 (2), 2009 167 MICROLITES AND ASSOCIATED OXIDE MINERALS FROM NAIPA PEGMATITES – ALTO LIGONHA – ZAMBEZIA - MOZAMBIQUE
    [Show full text]
  • EGU2016-11594, 2016 EGU General Assembly 2016 © Author(S) 2016
    Geophysical Research Abstracts Vol. 18, EGU2016-11594, 2016 EGU General Assembly 2016 © Author(s) 2016. CC Attribution 3.0 License. Isotope age of the rare metal pegmatite formation in the Kolmozero-Voron’ya greenstone belt (Kola region of the Fennoscandian shield): U-Pb (TIMS) microlite and tourmaline dating Nikolay Kudryashov, Ludmila Lyalina, Artem Mokrushin, Dmitry Zozulya, Nikolay Groshev, Ekaterina Steshenko, and Evgeniy Kunakkuzin Geological Institute of the KSC RAS, Apatity, Russian Federation ([email protected]) The Kolmozero-Voron’yagreenstone belt is located in the central suture zone, which separates the Murmansk block from the Central-Kola and the Keivy blocks. The belt is represented by volcano-sedimentary rocks of Archaean age of 2.9-2.5 Ga. Rare metal pegmatites (Li, Cs with accessory Nb, Ta, and Be) occur among amphibolite and gabbroid intrusions in the northwestern and southeastern parts of the belt. According to the Rb-Sr data, the age of pegmatites was considered to be 2.7 Ga. Until recently there was no generally accepted point of view on the origin of pegmatites. Now we have isotopic data for a range of rock complexes that could pretend to be parental granites for the rare metal pegmatites. These are granodiorites with the zircon age of 2733±Ma, and microcline and tourmaline granites, which Pb-Pb isochronal age on tourmaline from the tourmaline granite located near the deposit is estimated to be 2520±70 Ma. The pegmatite field of the Vasin Myl’k deposit with the lepidolite–albite– microcline–spodumene–pollucite association is located among amphibolites in the northwestern part of the belt.
    [Show full text]
  • Geochemical Alteration of Pyrochlore Group Minerals: Microlite Subgroup Gnrconv R. Luurpxrn Roonev C. Ewruc Ansrru.Cr
    AmericanMineralogist, Volume 77, pages l,79-188,1992 Geochemical alteration of pyrochlore group minerals: Microlite subgroup Gnrconv R. LuurpxrN Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag I, Menai, New South Wales 2234, Ans1nalla RooNev C. Ewruc Department of Geology, University of New Mexico, Albuquerque, New Mexico 87131, U.S.A. Ansrru.cr A qualitative picture of microlite stability is derived from known mineral assemblages and reactions in the simplified system Na-Ca-Mn-Ta-O-H. Results suggestthat microlite is stable under conditions of moderate to high 4*"* and aq^z*and low to moderate 4rnz*. Microlite is often replaced during the latter stagesof granitic pegmatite evolution by man- ganotantalite and fersmite or rynersonite, indicating increasingdq^z* ?fid 4Mn2*relative to a*.-. Primary (hydrothermal) alteration involves replacementof Na, F, and vacanciesby Ca and O, representedby the coupled substitutions ANaYF- ACaYOand AtrY! - ACaYO. Exchangereactions between microlite and fluid suggestconditions of relatively high pH, high aa,^z*,lowto moderate a.r, and low a".. during alteration by evolved pegmatite fluids at 350-550'C and 2-4 kbar. Secondary(weathering) alteration involves leaching ofNa, Ca, F, and O, representedby the coupled substitutions ANaYF - AEY!, ACaYO- AEYII and ACaxO - Alxfl. Up to 800/oof the A sites may be vacant, usually accompaniedby a comparablenumber of anion (X + Y) vacanciesand HrO molecules.Secondary alteration results from interaction with relatively acidic meteoric HrO at temperatures below 100 "C. In both types of alteration, the U content remains remarkably constant.Loss of radio- genic Pb due to long-term difftrsion overprints changesin Pb content associatedwith primary alteration in most samples.
    [Show full text]
  • Crystallization Processes and Solubility of Columbite-(Mn), Tantalite-(Mn), Microlite, Pyrochlore, Wodginite and Titanowodginite in Highly Fluxed Haplogranitic Melts
    Western University Scholarship@Western Scholarship@Western Electronic Thesis and Dissertation Repository 3-12-2018 10:30 AM Crystallization processes and solubility of columbite-(Mn), tantalite-(Mn), microlite, pyrochlore, wodginite and titanowodginite in highly fluxed haplogranitic melts Alysha G. McNeil The University of Western Ontario Supervisor Linnen, Robert L. The University of Western Ontario Co-Supervisor Flemming, Roberta L. The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Alysha G. McNeil 2018 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Earth Sciences Commons Recommended Citation McNeil, Alysha G., "Crystallization processes and solubility of columbite-(Mn), tantalite-(Mn), microlite, pyrochlore, wodginite and titanowodginite in highly fluxed haplogranitic melts" (2018). Electronic Thesis and Dissertation Repository. 5261. https://ir.lib.uwo.ca/etd/5261 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract Niobium and tantalum are critical metals that are necessary for many modern technologies such as smartphones, computers, cars, etc. Ore minerals of niobium and tantalum are typically associated with pegmatites and include columbite, tantalite, wodginite, titanowodginite, microlite and pyrochlore. Solubility and crystallization mechanisms of columbite-(Mn) and tantalite-(Mn) have been extensively studied in haplogranitic melts, with little research into other ore minerals. A new method of synthesis has been developed enabling synthesis of columbite-(Mn), tantalite-(Mn), hafnon, zircon, and titanowodginite for use in experiments at temperatures ≤ 850 °C and 200 MPa, conditions attainable by cold seal pressure vessels.
    [Show full text]
  • Mineralogy and Geochemical Evolution of the Little Three
    American Mineralogist, Volume 71, pages 406427, 1986 Mineralogy and geochemicalevolution of the Little Three pegmatite-aplite layered intrusive, Ramona,California L. A. SrnnN,t G. E. BnowN, Jn., D. K. Brno, R. H. J*rNs2 Department of Geology, Stanford University, Stanford, California 94305 E. E. Foono Branch of Central Mineral Resources,U.S. Geological Survey, Denver, Colorado 80225 J. E. Snrcr,nv ResearchDepartment, Gemological Institute of America, 1660 Stewart Street,Santa Monica, California 90404 L. B. Sp.c,uLDrNG" JR. P.O. Box 807, Ramona,California 92065 AssrRAcr Severallayered pegmatite-aplite intrusives exposedat the Little Three mine, Ramona, California, U.S.A., display closelyassociated fine-grained to giant-texturedmineral assem- blageswhich are believed to have co-evolved from a hydrous aluminosilicate residual melt with an exsolved supercriticalvapor phase.The asymmetrically zoned intrusive known as the Little Three main dike consists of a basal sodic aplite with overlying quartz-albite- perthite pegmatite and quartz-perthite graphic pegmatite. Muscovite, spessartine,and schorl are subordinate but stable phasesdistributed through both the aplitic footwall and peg- matitic hanging wall. Although the bulk composition of the intrusive lies near the haplo- granite minimum, centrally located pockets concentratethe rarer alkalis (Li, Rb, Cs) and metals (Mn, Nb, Ta, Bi, Ti) of the system, and commonly host a giant-textured suite of minerals including quartz, alkali feldspars, muscovite or F-rich lepidolite, moderately F-rich topaz, and Mn-rich elbaite. Less commonly, pockets contain apatite, microlite- uranmicrolite, and stibio-bismuto-columbite-tantalite.Several ofthe largerand more richly mineralized pockets of the intrusive, which yield particularly high concentrationsof F, B, and Li within the pocket-mineral assemblages,display a marked internal mineral segre- gation and major alkali partitioning which is curiously inconsistent with the overall alkali partitioning of the system.
    [Show full text]
  • Alphabetical List
    LIST L - MINERALS - ALPHABETICAL LIST Specific mineral Group name Specific mineral Group name acanthite sulfides asbolite oxides accessory minerals astrophyllite chain silicates actinolite clinoamphibole atacamite chlorides adamite arsenates augite clinopyroxene adularia alkali feldspar austinite arsenates aegirine clinopyroxene autunite phosphates aegirine-augite clinopyroxene awaruite alloys aenigmatite aenigmatite group axinite group sorosilicates aeschynite niobates azurite carbonates agate silica minerals babingtonite rhodonite group aikinite sulfides baddeleyite oxides akaganeite oxides barbosalite phosphates akermanite melilite group barite sulfates alabandite sulfides barium feldspar feldspar group alabaster barium silicates silicates albite plagioclase barylite sorosilicates alexandrite oxides bassanite sulfates allanite epidote group bastnaesite carbonates and fluorides alloclasite sulfides bavenite chain silicates allophane clay minerals bayerite oxides almandine garnet group beidellite clay minerals alpha quartz silica minerals beraunite phosphates alstonite carbonates berndtite sulfides altaite tellurides berryite sulfosalts alum sulfates berthierine serpentine group aluminum hydroxides oxides bertrandite sorosilicates aluminum oxides oxides beryl ring silicates alumohydrocalcite carbonates betafite niobates and tantalates alunite sulfates betekhtinite sulfides amazonite alkali feldspar beudantite arsenates and sulfates amber organic minerals bideauxite chlorides and fluorides amblygonite phosphates biotite mica group amethyst
    [Show full text]
  • New Mineral Names*,†
    American Mineralogist, Volume 106, pages 1186–1191, 2021 New Mineral Names*,† Dmitriy I. Belakovskiy1 and Yulia Uvarova2 1Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18 korp. 2, Moscow 119071, Russia 2CSIRO Mineral Resources, ARRC, 26 Dick Perry Avenue, Kensington, Western Australia 6151, Australia In this issue This New Mineral Names has entries for 10 new species, including huenite, laverovite, pandoraite-Ba, pandoraite- Ca, and six new species of pyrochlore supergroup: cesiokenomicrolite, hydrokenopyrochlore, hydroxyplumbo- pyrochlore, kenoplumbomicrolite, oxybismutomicrolite, and oxycalciomicrolite. Huenite* hkl)]: 6.786 (25; 100), 5.372 (25, 101), 3.810 (51; 110), 2.974 (100; 112), P. Vignola, N. Rotiroti, G.D. Gatta, A. Risplendente, F. Hatert, D. Bersani, 2.702 (41; 202), 2.497 (38; 210), 2.203 (24; 300), 1.712 (60; 312), 1.450 (37; 314). The crystal structure was solved by direct methods and refined and V. Mattioli (2019) Huenite, Cu4Mo3O12(OH)2, a new copper- molybdenum oxy-hydroxide mineral from the San Samuel Mine, to R1 = 3.4% using the synchrotron light source. Huenite is trigonal, 3 Carrera Pinto, Cachiyuyo de Llampos district, Copiapó Province, P31/c, a = 7.653(5), c = 9.411(6) Å, V = 477.4 Å , Z = 2. The structure Atacama Region, Chile. Canadian Mineralogist, 57(4), 467–474. is based on clusters of Mo3O12(OH) and Cu4O16(OH)2 units. Three edge- sharing Mo octahedra form the Mo3O12(OH) unit, and four edge-sharing Cu-octahedra form the Cu4O16(OH)2 units of a “U” shape, which are in Huenite (IMA 2015-122), ideally Cu4Mo3O12(OH)2, trigonal, is a new mineral discovered on lindgrenite specimens from the San Samuel turn share edges to form a sheet of Cu octahedra parallel to (001).
    [Show full text]
  • The Role and Significance of Pegmatites in the Central Alps. Proxies of the Exhumation History of the Alpine Nappe Stack in the Lepontine Dome
    Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2009-2010 THE ROLE AND SIGNIFICANCE OF PEGMATITES IN THE CENTRAL ALPS. PROXIES OF THE EXHUMATION HISTORY OF THE ALPINE NAPPE STACK IN THE LEPONTINE DOME Ph.D. candidate: ALESSANDRO GUASTONI Tutors: Prof. GILBERTO ARTIOLI, Prof. GIORGIO PENNACCHIONI Cycle:XXIV Abstract The pegmatitic field is located between Domodossola town (Western-Central Alps) and the Masino-Bregaglia Oligocene intrusion (Central Alps) ). Most of the pegmatitic dikes are hosted into the Southern Steep Belt (SSB), an alpine migmatitic unit characterized by high temperature greenschist and amphibolitic facies related to Barrovian metamorphism. Swiss authors aged some aplite-pegmatites between 29-26 m.y. Most of pegmatitic dikes (>90%) are composed by K-feldspar and subordinate quartz+ muscovite. A small population of more “geochemically evolved” population of pegmatites respectively belong to the LCT (lithium, cesium, tantalum) and NYF (niobium, yttrium, fluorine) families. Studies will focuse: to isotopes to define age of crystallizations and rate of coolings of deformed and miarolitic pegmatites; to geochemistry and relate the genesis of Alpine pegmatites to migmatites terrains of the Alpine Barrovian-type metamorphic belt or to granitic-tonalitic liquid melts of Masino-Bregaglia intrusion. Introduction Most of the pegmatitic dikes are hosted by the Southern Steep Belt (SSB), an alpine migmatitic unit, which includes several Lepontine nappes like the Antigorio, the Monte Rosa, the Camughera-Moncucco- Isorno-Orselina and the Adula. Alpine metamorphism in Central Alps is poliphasic and characterized by high temperature greenschist and amphibolitic facies related to Barrovian metamorphism during Oligocene-Miocene age (Burg & Gerya, 2005; Burri et al., 2005; Maxelon & Mancktelow, 2005).
    [Show full text]
  • Extraction and Separation of Tantalum and Niobium from Mozambican Tantalite by Solvent Extraction in the Ammonium Bifluoride-Octanol System
    EXTRACTION AND SEPARATION OF TANTALUM AND NIOBIUM FROM MOZAMBICAN TANTALITE BY SOLVENT EXTRACTION IN THE AMMONIUM BIFLUORIDE-OCTANOL SYSTEM by KABANGU MPINGA JOHN Dissertation submitted in partial fulfillment of the requirements for the degree of MSc (Applied Science): Chemical Technology Department of Chemical Engineering Faculty of Engineering, the Built Environment and Information Technology Supervisor: Prof. Philip Crouse University of Pretoria © University of Pretoria DECLARATION I, Kabangu Mpinga John, student No. 28140045, hereby declare that all the work provided in this dissertation is to the best of my knowledge original (excepted where cited) and that neither the whole work nor any part of it has been, or is to be, submitted for another degree at University of Pretoria or any other University or tertiary education institution or examining body. SIGNATURE……………………………………………………………………………………… DATE………………………………………………………………………………………………. KABANGU MPINGA JOHN I SYNOPSIS EXTRACTION AND SEPARATION OF TANTALUM AND NIOBIUM FROM MOZAMBICAN TANTALITE BY SOLVENT EXTRACTION IN THE AMMONIUM BIFLUORIDE-OCTANOL SYSTEM Autor: Kabangu Mpinga John Supervisor: Prof. Philip Crouse Department: Chemical Engineering Degree: MSc (Applied Science): Chemical Technology The principal aim of this research was to determine the optimum conditions of extraction and separation of niobium and tantalum with octanol as solvent, from Mozambican tantalite using ammonium bifluoride as an alternative to hydrofluoric acid. The extraction of niobium and tantalum from tantalite can be divided into three activities, viz., acid treatment of the ore to bring the niobium and tantalum values into solution, separation of niobium and tantalum by solvent extraction and preparation of pure niobium pentoxide and tantalum pentoxide by precipitation followed by calcination. An initial solution was prepared by melting a mixture of tantalite and ammonium bifluoride followed by leaching of the soluble component with water and separation of the solution by filtration.
    [Show full text]
  • Eparating the Columbium and Tantalum Salts Or Oxides from Each Other
    TANTALUM, COLUMBIUM, AND FERROCOLUMBIUM A. Commodity Summary Tantalum is used in the electronics industry, as well as in aerospace and transportation applications. Columbium (the commonly used synonym for the element niobium) is used as an alloying element in steels and in superalloys. Tantalum and columbium are often found together in pyrochlore and baripyrochlore, the main columbium containing minerals, as well as in columbite. These minerals contain relatively small amounts of tantalum, pyrochlore, and baripyrochlore, having a columbium pentoxide-to-tantalum pentoxide ratio of 200 to 1 or greater.1 Columbite contains slightly larger amounts (up to eight percent) of tantalum.2 Tantalite is the primary source of tantalum pentoxide, and contains small amounts of columbium pentoxide. Microlite is another source of tantalum pentoxide. Tantalum is also recovered from tin slags.3 There has been no significant mining of tantalum or columbium ores in the United States since 1959. Producers of columbium metal and ferrocolumbium use imported concentrates, columbium pentoxide, and ferrocolumbium. Tantalum products are made from imported concentrates and metal, and foreign/domestic scrap.4 Ferrocolumbium is an alloy of iron and columbium. Ferrocolumbium is used principally as an additive to improve the strength and corrosion resistance of steel used in high strength linepipe, structural members, lightweight components in cars and trucks, and exhaust manifolds. High purity ferrocolumbium is used in superalloys for applications such as jet engine components, rocket assemblies, and heat-resisting and combustion equipment.5 Exhibit 1 summarizes the principal producers of tantalum, columbium and ferrocolumbium in the United States in 1992. Only Cabot Corporation and Shieldalloy Metallurgical Corporation use ores as their starting material.6 B.
    [Show full text]
  • New Mexico Bureau of Geology and Mineral Resources Rockhound Guide
    New Mexico Bureau of Geology and Mineral Resources Socorro, New Mexico Information: 505-835-5420 Publications: 505-83-5490 FAX: 505-835-6333 A Division of New Mexico Institute of Mining and Technology Dear “Rockhound” Thank you for your interest in mineral collecting in New Mexico. The New Mexico Bureau of Geology and Mineral Resources has put together this packet of material (we call it our “Rockhound Guide”) that we hope will be useful to you. This information is designed to direct people to localities where they may collect specimens and also to give them some brief information about the area. These sites have been chosen because they may be reached by passenger car. We hope the information included here will lead to many enjoyable hours of collecting minerals in the “Land of Enchantment.” Enjoy your excursion, but please follow these basic rules: Take only what you need for your own collection, leave what you can’t use. Keep New Mexico beautiful. If you pack it in, pack it out. Respect the rights of landowners and lessees. Make sure you have permission to collect on private land, including mines. Be extremely careful around old mines, especially mine shafts. Respect the desert climate. Carry plenty of water for yourself and your vehicle. Be aware of flash-flooding hazards. The New Mexico Bureau of Geology and Mineral Resources has a whole series of publications to assist in the exploration for mineral resources in New Mexico. These publications are reasonably priced at about the cost of printing. New Mexico State Bureau of Geology and Mineral Resources Bulletin 87, “Mineral and Water Resources of New Mexico,” describes the important mineral deposits of all types, as presently known in the state.
    [Show full text]