DOCSLIB.ORG

Grunerite from the Shinyama Ore Deposit, Kamaishi Mine

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Grunerite from the Shinyama Ore Deposit, Kamaishi Mine Canadian Mineralogist Vol. 21, pp. 517-528(1983) GRUNERITEFROM THE SHINYAMA ORE DEPOSIT,KAMAISHI MINE, JAPAN ETSUO UCHIDA,8 GeologicalInstitute, Facalty of Scienc?,University of Tokyo, 7-3-l Hongo, Bunkyo-ku, Tokyo 113,Japan ABSTRACT on compositionsof amphibole determinedby the electron-probemicroanalyzer, reveals that most are, Most of the clinopyroxenein the clinopyroxeneskam that in fact, cummingtonite-grunerite containing only a contains the 4D copper orebody of the Shinyama ore small calcium component,Grunerite is common in deposit(Japan) was alteredto amphibole owing to late-stage metamorphosediron-formations (cl, Mueller 1960), decreaseoftemperature. Two amphibole speciesare found: Ca-amphibole and cummingtonite-grunerite; the latter is and cummingtonite is widespreadin metabasicrocks rarely found in skarn-typeore deposits.In exoskarnsderiv- in the amphibolite facies. But cummingtonite- ed from limestone, the following zonal arrangementis grunerite is rare.in skarn-typeore deposits.In this observed from the limestone to the igneous rock: paper, the amphibolesoccurring in skarns around cummingtonite-grunerite skarn, Ca-amphibole skarn, the 4D orebody of the Shinyamadeposit are describ- (clinopyroxene skarn) and garnet skarn. This arrangement ed, and their thermochemicalconditions of forma- is attributable to the increasein the chemicalpotential of tion are elucidated. CO2 toward the limestone. GEOLoGYoF THE KAMATSHIMINING Keywords: cummingtonite-grunerite, Kamaishi mine, Shinyama deposit, skarn, zonal arrangement,phase Drsrnrcr ANDDEscRrprroN oF THEDEposrrs equilibria, thermochemicaldata, X(CO), Japan. The Kamaishi mine, located in the easternmargin Souuernr of Kitakami massif,is typical of iron-copper skarn- type depositsin Japan.The mine is locatednear the Le gite 4D du gisement cuprifbre de Shinyama (Japon) Hayachine-Goyozan tectonic zone. Mesozoic to se pr6sentedans un skarn i clinopyrox0ne.Ce pyroxdne Paleozoicsedimentary formations and igneousrocks s'esten grandepartie alterden amphibolei la suite d'une baissetardive de la temp6rature.Deux espdcesd'amphi- are distributed around the mining district. The ore bole sont repr6sent6es:I'une, amphibolecalcique et I'au- depositsof the Kamaishimine occur nearthe boun- tre, membre de la s6riecummingtonite-grun6rite, rarement dary betweenthe Nagaiwa-Onimaru limestonewhich trouvde dansles gisementsde type skarn. Dans les exoskarns is of Carboniferousage and the Ganidakeigneous d€riv6s de calcaire, on observeles zonessuivantes. du cal- complex of Early Cretaceousage. The Iimestoneis caire vers la roche ign€e: skarn d cummingtonite-grundriie, the host rock of the skarns. The Shinyama ore skarn i amphibolecalcique, (skarn i clinopyroxdne)et skarn depositis located on the west side of the Ganidake d grenat. On peut attribuer cette disposition en zonesi igneouscomplex and is the largestin the Kamaishi l'augmentation du potentiel chimique du CO2 en direction du calcaire. mining district. It is composedof thirteen orebodies (Traduit par la R6dacrion) which may be subdividedinto three types: iron, cop- per and iron-copper. The skarn can be roughly divid- Mots-cl4s: cummingtonite-grundrite, mine de Kamaishi, ed into clinopyroxeneskarn and garnet skarn; the qrsq-n9ntde Shinyama, skarn, distribution en zones, former containscopper orebodies and the latter iron 6qujlibre de phases, donn6es thermochimiques, or iron-copper orebodies. Grunerite occurs in X(CO), Japon: clinopyroxeneskarn, which enclosesthe largestcop- per orebody, called 4D, in the Shinyamaore deposit. IurnooucrroN The readerwill find a more detaileddescription of the Kamaishi mining:district in Hamabe & Yano Clinopyroxeneskarn of the 4D copper orebody (r976). of the Shinyamadeposit of the Kamaishi mine under- went strong late-stage alteration. Most of the THE SKARNSAnouNo THE4D AND7D OREBoDIES clinopyroxenein the skarn was altered to arnphibole, previously consideredto be Ca-amphibole(actinolite The skarns.uound the 4D copper and 7D iron- to common hornblende).The presentstudy, based copperorebodies of the Shinyamaore deposithave beendescribed in detail by Uchida & Iiyama (1982); only a summary is given here. *Presentaddress: Laboratoire de Min6ralogieet G6ologie The skarns are formed along the boundary be- Appliqude, Universitd Catholique de Louvain, 1348 tween limestone and diorite to diorite porphyry Louvainla-Neuve, Belgique. belonging to the Ganidake igneouscomplex (Fig. l). 517 518 THE CANADIAN MINERALOGIST \/ \/ \/ \/ \/ \z \z \u \ /\ z\ /\ /\ / /r u r zt /\ \/ \/ \/ \/ \ \/ \/ \/ \/ ++++ /\ ,\ /\./\ / /\ /\ /\ /\ %r. ore body \/ \/ \/ \/ \ \/ \/ \/ \/ \ ++++ /\ /\ /\ /\ ,/ /\ /\ /\ /\ / \/. \/ \/ \./ \ \,/ \/ \/ \,, \ @re-cuarewat FFFFf, )< )( >(,.,. > ffi Cu ore body \/ \/ \/ \/ \ ,\ a\ a \ /\ / cometstom \/ \/ \/ \/ \ Il3 /\ /\ z\ /\,7 )( ,'( )( \/ \/ \,, \/ \ cnr stcrn \ /\ /\ /\ / )" )')( @ FJT Limestone E \/ \/ \/ \ t\ 2\ 1':' 71 F=i 51q1s ><)v4< -l Homfels a a a.l\ -500 -4@ -300 -zn Frc. l. Gbologicplan at the 5O&metrelevel in the vicinity of the Shinyama4D copper and 7D iron-copper orebodies (after the Kamaishi Mining Company, Ltd.). They show the following ,[rangement of zonescross- OCCURRENCE AND DISTRIBUTION OF AMPHIBOLE ed perpendicularto the boundary, from the limestone toward the igneousrock: clinopyroxeneskarn (that Amphibole occurs in all skarn zones, but is enclosesthe 4D copperorebody), garnet skarn, the especiallyabundant in clinopyroxeneskarn, garnet 7D iron-copper orebody, garnet-clinopyroxene skarn,the iron-copper orebody,epidote-amphibole skarn, epidote-clinopyroxene skarn, epidote- skarnand plagioclase-amphiboleskarn. Amphibole amphiboleskarn and plagioclase-amphiboleskarn. in the former three skarns is consideredto be an The latter three are not well developed,compared alteration product of clinopyroxene,and that in the with the former. latter two skarnsis consideredto be derived from Clinopyroxeneskarn is well developedin the up- diorite to diorite porphyry. Amphibolitization of per levels and narrows abruptly toward the lower clinopyroxeneis weak in garnet-clinopyroxeneand levels.Most of the clinopyroxeneis strongly altered epidote-clinopyroxeneskarns. to amphibole and is, at present,rarely found, Garnet The presenceof relict clinopyroxeneand of Ca- skarn, Iocatedon the limestoneside of the 7D iron- amphibolepseudomorphs after clinopyroxene@ig. copper orebody, consistsmainly of coarse-grained 38, D) shows that clinopyroxeneskarn was once anisotropic garnet with a moderate amount of composedmainly of clinopyroxene.This skarn is, clinopyroxene. Garnet-clinopyroxeneskarn, located at present,composed mainly of amphiboles,calcite on the igneous rock side of the 7D iron-copper and quartz. Clinopyroxeneis observedlocally near orebody, is composedmainly of isotropic to slight- the networksof anisotropicgarnet. Such strong am- ly anisotropic garnet and clinopyroxene.Clinopyrox- phibolitization is a typical featureof the 4D copper enein garnet and garnet-clinopyroxeneskarns is not orebody and is not observedin the other copper so strongly alteredto'amphibole. Judging from the orebodies(2D, 3D,5D and 8D) of the deposit. TiO2 content, and from the size and form of the Three types of amphibole, cummingtonite- garnet crystals,garnet skarn is consideredto be deriv- grunerite, actinolite and hornblende,are identified ed from limestone, and garnel-clinopyroxeneskarns in the clinopyroxeneskarn. The following regulari- from diorite to diorite porphyry (cf Uchida & Iiyama ty of distribution is recognizedfor theseamphiboles; 1982).A network of anisotropic garnet is formed becauseit is not very easyto distinguishsome Mg- locally along fractures in clinopyroxeneskarn; the poor actinolite from common hornblende, thesetwo garnetis similar to that composingthe garnetskarn. amphiboles are called Ca-amphibole for conve- GRUNERITE FROM THE SHINYAMA ORE DEPOSIT. JAPAN 519 500M1N430 --+N o OO OOOO a a o a a$Y - E ,""" .6 !v 'o oo ro oi )o ol ooo .c/.i or ^s' ooo F {f $g 5s *'"1t?'50 Ftc.2.-Distribution of amphibolesin clinopyroxeneskarn near N430 of the s@-metrelevel of the Shinyzrmaore deposit. This areacorresponds to that surroundedby dotted linesin Figure l. Parenthesesindicaie a small quantity. Numbers are samplenumbers. Legend: seeFigure l. nience.Figure 2 showsthe distribution of theseam- Ca-amphibole is generally idiomorphic to phiboles in the clinopyroxeneskarn near N430 of the hypidiomorphic and may contain relics of 500-metrelevel. Many garnet networks are observ- clinopyroxene (Fig. 3D), whereas no relics of ed here (Fig. 3A). There is a tendency for Ca- clinopyroxene are observed in cummingtonite- amphiboleto dominate where garnet networks oc- grunerite. The color of the Ca-amphibolevaries from cur, whereascummingtonite-grunerite dominates colorlessto dark greenaccording to its Al content. elsewhere.Since the garnetsare formed along frac- Ca-amphiboleis accompaniedby small amountsof tures in clinopyroxene skarn, the formation and calcite,quartz and magnetite.Though it is not easy distributionof the amphibolesare thought to be con- to distinguishactinolite from hornblende in some trolled by the fracture system. cases,there is a tendencyfor hornblendeto dominate wheregarnet networks occur. The amount of acti- Cummingtonite-gruneriteis not common in skarn- nolite increaseswith distancefrom the networks. Ac- type ore deposits.It hasbeen reported only from the tinolite rimmed with hornblendeis sometimesobserv- Obira and Mitate mines in Japan (Miyahisa 1958, ed, which may indicatethe replacementof actinolite
Load more

Recommended publications
  • Optical Properties of Common Rock-Forming Minerals
    AppendixA __________ Optical Properties of Common Rock-Forming Minerals 325 Optical Properties of Common Rock-Forming Minerals J. B. Lyons, S. A. Morse, and R. E. Stoiber Distinguishing Characteristics Chemical XI. System and Indices Birefringence "Characteristically parallel, but Mineral Composition Best Cleavage Sign,2V and Relief and Color see Fig. 13-3. A. High Positive Relief Zircon ZrSiO. Tet. (+) 111=1.940 High biref. Small euhedral grains show (.055) parallel" extinction; may cause pleochroic haloes if enclosed in other minerals Sphene CaTiSiOs Mon. (110) (+) 30-50 13=1.895 High biref. Wedge-shaped grains; may (Titanite) to 1.935 (0.108-.135) show (110) cleavage or (100) Often or (221) parting; ZI\c=51 0; brownish in very high relief; r>v extreme. color CtJI\) 0) Gamet AsB2(SiO.la where Iso. High Grandite often Very pale pink commonest A = R2+ and B = RS + 1.7-1.9 weakly color; inclusions common. birefracting. Indices vary widely with composition. Crystals often euhedraL Uvarovite green, very rare. Staurolite H2FeAI.Si2O'2 Orth. (010) (+) 2V = 87 13=1.750 Low biref. Pleochroic colorless to golden (approximately) (.012) yellow; one good cleavage; twins cruciform or oblique; metamorphic. Olivine Series Mg2SiO. Orth. (+) 2V=85 13=1.651 High biref. Colorless (Fo) to yellow or pale to to (.035) brown (Fa); high relief. Fe2SiO. Orth. (-) 2V=47 13=1.865 High biref. Shagreen (mottled) surface; (.051) often cracked and altered to %II - serpentine. Poor (010) and (100) cleavages. Extinction par- ~ ~ alleL" l~4~ Tourmaline Na(Mg,Fe,Mn,Li,Alk Hex. (-) 111=1.636 Mod. biref.
    [Show full text]
  • ASBESTOS: MINERALOGY, HEALTH HAZARDS and PUBLIC POLICY Helen M
    ASBESTOS: MINERALOGY, HEALTH HAZARDS AND PUBLIC POLICY Helen M. Lang Department of Geology and Geography West Virginia University P.O. Box 6300 Morgantown, West Virginia 26506-6300 [email protected] Sid P. Halsor Department of GeoEnvironmental Science & Engineering Wilkes University Wilkes-Barre, Pennsylvania 18766 [email protected] BACKGROUND Asbestos refers to certain minerals that have a fibrous habit and are useful for their insulating, heat and chemically resistant properties. Asbestos has been used extensively for over a century in electrical and heat insulation, fireproofing materials, brake and clutch linings, construction materials, filters and many other applications. Recently, the U.S. has severely restricted the use of asbestos, and has a program for removing asbestos from schools and other public buildings (See Gunter, 1994; Ross, 1995 and references therein). In this laboratory exercise you will have an opportunity to examine the crystal structures, optical properties and health hazards of the common asbestos minerals. The laboratory will reinforce optical microscopic skills that you have learned in mineralogy and show you how mineralogy can be critical to understanding a current public policy issue. Although mineralogists reserve the designation asbestos for fibrous material with a length:width ratio (aspect ratio) of at least 10: 1 (Skinner, et al., 1988), asbestos is defined by OSHA (U.S. Occupational Safety and Health Administration, 1972; Web address is given below) as mineral material composed of any of the six silicate minerals in Table 1 with a length:width ratio of3:1 or greater, diameter less than 5 µm and length greater than 5 µm. Table 1.
    [Show full text]
  • The Crystal Structure and Cation Distribution of a Grunerite
    Mineral. Soc. Amer. Spec. Pap. 2, 95-100 (1969). THE CRYSTAL STRUCTURE AND CATION DISTRIBUTION OF A GRUNERITE LARRY W. FINGER Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20008 ABSTRACT Three-dimensional, counter-measured, X-ray diffraction data have been used in the refinement of the anisotropic atomic parameters and cation distribution of a grunerite from the Wabush iron formation, Labrador, Canada. The occupancies of the cation sites were determined by assuming the chemical composition of (Fe6.2Mgo.8)Si,O,,(OH)15Fo.5 and constraining the occupancies so that each of the four independent sites was full of Fe + Mg and the overall chem- istry matched the formula. The resulting occupancies for Mg are as follows: M(l), 0.152 ± 0.008; M(2), 0.227 ± 0.007; M(3), 0.112 ± 0.012; and M(4), 0.015 ± 0.008. These occupancies are in agreement with the previous deter- minations for this mineral. The refinement of the crystal structure of a grunerite A. = l. 93991 A). The unit-cell constants were refined with was undertaken to investigate the ordering of Fe and Mg the lattice-constant refinement program of Burnham in an amphibole containing very little Mg. The technique (1962). The observed data, corrected for absorption, film of least-squares was used to assign the average chemical shrinkage, camera radius, and eccentricity errors, are a = composition of each site. This mineral series has been stud- 9.5642 ± 0.0007 A, b = 18.393 ± 0.002 A, c = 5.3388 ied by Ghose and Hellner (1959) and Ghose (1961), who ± 0.0003 A, (3 = 1Ol.892° -+- 0.003°, V = 919.0 ± 0.2 A3.
    [Show full text]
  • The Crystal Structure and Cation Distribution of a Grunerite
    Mineral. Soc. Amer. Spec. Pap. 2, 95-100 (1969). THE CRYSTAL STRUCTURE AND CATION DISTRIBUTION OF A GRUNERITE LARRY W. FINGER Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20008 ABSTRACT Three-dimensional, counter-measured, X-ray diffraction data have been used in the refinement of the anisotropic atomic parameters and cation distribution of a grunerite from the Wabush iron formation, Labrador, Canada. The occupancies of the cation sites were determined by assuming the chemical composition of (Fe..,Mg..,ISisO,,(OH),..F.:. and constraining the occupancies so that each of the four independent sites was full of Fe + Mg and the overall chem- istry matched the formula. The resulting occupancies for Mg are as follows; M(l), 0.152 ::!:0.008: M(2), 0.227 ::!: 0.007; M(3), 0.112 ::!: 0.012; and M(4), 0.015 :!: 0.008. These occupancies are in agreement with the previous deter- minations for this mineral. The refinement of the crystal structure of a grunerite A = 1.93991A). The unit-cell constants were refined with was undertaken to investigat~ the ordering of Fe and Mg the lattice-constant refinement program of Burnham in an amphibole containing very little Mg. The technique (1962). The observed data, corrected for absorption, film of least-squares was used to assign the average chemical shrinkage, camera radius, and eccentricity errors, are a = composition of each site. This mineral series has been stud- 9.5642 ::!: 0.0007 A, b = 18.393 ::!: 0.002 A., c = 5.3388 ied by Ghose and Hellner (1959) and Ghose (1961), who ::!: 0.0003 A, f3 = 101.892° ::!::0.003°, V = 919.0 ::!: 0.2 A3.
    [Show full text]
  • The Effects of Metamorphism on O and Fe Isotope Compositions in the Biwabik Iron Formation, Northern Minnesota
    Contrib Mineral Petrol DOI 10.1007/s00410-007-0244-2 ORIGINAL PAPER The effects of metamorphism on O and Fe isotope compositions in the Biwabik Iron Formation, northern Minnesota Elizabeth Valaas Hyslop Æ John W. Valley Æ Clark M. Johnson Æ Brian L. Beard Received: 26 April 2007 / Accepted: 31 July 2007 Ó Springer-Verlag 2007 Abstract The Biwabik Iron Formation of Minnesota suggest that both reflect cooling, where the closure temper- (1.9 Ga) underwent contact metamorphism by intrusion of ature for Fe was higher than for O. The net effect of the Duluth Complex (1.1 Ga). Apparent quartz–magnetite metamorphism on d18O–d56Fe variations in magnetite is a 18 56 oxygen isotope temperatures decrease from *700°C at the strong increase in d OMt and a mild decrease in d Fe with contact to *375°C at 2.6 km distance (normal to the contact increasing metamorphic grade, relative to the isotopic in 3D). Metamorphic pigeonite at the contact, however, compositions that are expected at the low temperatures of indicates that peak temperatures were greater than 825°C. initial magnetite formation. If metamorphism of Iron The apparent O isotope temperatures, therefore, reflect Formations occurs in a closed system, bulk O and Fe isotope cooling, and not peak metamorphic conditions. Magnetite compositions may be preserved, although re-equilibration was reset in d18O as a function of grain size, indicating that among the minerals may occur for both O and Fe isotopes. isotopic exchange was controlled by diffusion of oxygen in magnetite for samples from above the grunerite isograd.
    [Show full text]
  • Relationships Between Crystal Structure, Bonding and Thermal Stability of Amphiboles
    RELATIONSHIPS BETWEEN CRYSTAL STRUCTURE, BONDING AND THERMAL STABILITY OF AMPHIBOLES by KWO-LING CHYI Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geological Sciences APPROVED: G. V. Gibbs, Co-chairman D. A. Hewitt, Co-chairman F. D. Bloss M. C. Gilbert J. D. Rimstidt June, 1987 Blacksburg, Virginia Relationships between crystal structure, bonding and thermal stability of amp hiboles by Kwo-Ling Chyi Gerald V. Gibbs, Co-Chairman David A. Hewitt, Co-Chairman Dept. of Geologic~ Sciences (ABSTRACT) The complexities in structure and chemical composition of the amphiboles and the wide range of their occurrence suggest that the amphiboles are potential index minerals for the physical conditions of their formation. Hydrothermal stability studies of several amphibole end- members have demonstrated that the FeMg_1 substitution produces a wide spread in thermal stability. The crystal structure, upon substitution, responds to the differences in cation size and site occupancy, but the changes are small. In order to correlate the observed stability variation with the observed differences in crystal structure of amphiboles, structure parameters as well as calculated bond strengths, Madelung site energies, and average bond overlap populations obtained from Extended Hiickel Molecular Orbital (EHMO) calculation for different cation sites, were examined. Among the examined structural parameters, calculated Madelung site potentials, and bond strength, only the parameters involving bonds between the M(l)- and M(3)-cations with OH show higher correlations with the thermal stability as compared to those of the M(2)- and M(4)-cations.
    [Show full text]
  • Phase Relationships in Grunerite–Garnet-Bearing Amphibolites in The
    J. metamorphic Geol., 2005, 23, 1–17 doi:10.1111/j.1525-1314.2005.00554.x Phase relationships in grunerite–garnet-bearing amphibolites in the system CFMASH, with applications to metamorphic rocks from the Central Zone of the Limpopo Belt, South Africa A. ZEH1 ,T.J.B.HOLLAND2 &R.KLEMD1,3 1Mineralogisches Institut, Universita¨tWu¨rzburg, Am Hubland, D-97074 Wu¨rzburg, Germany ([email protected]) 2Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK 3Rand Afrikaans University, Geology Department, Johannesburg, South Africa ABSTRACT A petrogenetic grid in the model system CaO–FeO–MgO–Al2O3–SiO2–H2O is presented, illustrating the phase relationships among the minerals grunerite, hornblende, garnet, clinopyroxene, chlorite, olivine, anorthite, zoisite and aluminosilicates, with quartz and H2O in excess. The grid was calculated with the computer software THERMOCALC, using an upgraded version of the internally consistent thermodynamic dataset HP98 and non-ideal mixing activity models for all solid solutions. From this grid, quantitative phase diagrams (P–T pseudosections) are derived and employed to infer a P–T path for grunerite– garnet-bearing amphibolites from the Endora Klippe, part of the Venetia Klippen Complex within the Central Zone of the Limpopo Belt. Agreement between calculated and observed mineral assemblages and garnet zonation indicates that this part of the Central Zone underwent a prograde temperature and pressure increase from c. 540 °C/4.5 kbar to 650 °C/6.5 kbar, followed by a post-peak metamorphic pressure decrease. The inferred P–T path supports a geotectonic model suggesting that the area surrounding the Venetia kimberlite pipes represents the amphibolite-facies roof zone of migmatitic gneisses and granulites that occur widely within the Central Zone.
    [Show full text]
  • A Risk Assessment for Exposure to Grunerite Asbestos (Amosite) in an Iron Ore Mine
    Proc. Natl. Acad. Sci. USA Vol. 96, pp. 3412–3419, March 1999 Colloquium Paper This paper was presented at the National Academy of Sciences colloquium ‘‘Geology, Mineralogy, and Human Welfare,’’ held November 8–9, 1998 at the Arnold and Mabel Beckman Center in Irvine, CA. A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine R. P. NOLAN*†,A.M.LANGER*, AND RICHARD WILSON‡ *Environmental Sciences Laboratory, Brooklyn College of The City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210; and ‡Harvard University, 9 Oxford Street Rear, Cambridge, MA 02138 ABSTRACT The potential for health risks to humans In addition, lung content analysis using ATEM was used to exposed to the asbestos minerals continues to be a public characterize the fiber concentrations found in lung tissues of health concern. Although the production and use of the individuals who developed asbestos-related diseases after ex- commercial amphibole asbestos minerals—grunerite (amos- posure. The results of the air sampling program are used to ite) and riebeckite (crocidolite)—have been almost completely calculate the mine work required to inhale a similar number of eliminated from world commerce, special opportunities for fibers as that found in the lungs of mesothelioma cases. potentially significant exposures remain. Commercially viable The exposures measured in the iron ore mine are several deposits of grunerite asbestos are very rare, but it can occur factors of ten lower than the occupational exposures that as a gangue mineral in a limited part of a mine otherwise occurred in the studied groups. Unlike the comparisons of lung thought asbestos-free.
    [Show full text]
  • The Thermal Decomposition of Amosite by A
    MINERALOGICAL MAGAZINE JOURNAL OF THE MINERALOGICAL SOCIETY Vol. 35 September 1965 No. 271 The thermal decomposition of amosite By A. A. HODGSON Cape Asbestos Fibres Limited, Barking, Essex, A. G. FREEMAN, 1 and H. F. W. TAYLOR Department of Chemistry, University of Aberdeen [Read 17 September 1964] Summary. When amosite (fibrous grunerite, F%.sMgl.sSisO~(OH)~), is heated in argon or nitrogen, physically combined water is lost up to 500-700 ~ C. Above 500~ (static) or 700~ (dynamic), dehydroxylation occurs endothermieally, giving a pyroxene as the main product. Under dynamic heating conditions, part of the hydroxyl water is lost as hydrogen, with concurrent oxidation of the iron. At about 1000 ~ C the pyroxene is decomposed to olivine and cristobalite ; at about 1100 ~ C melting begins. In oxygen or air, physically combined water is again lost below 500-700 ~ C. At 350-1200 ~ C a sequence of overlapping dehydrogenation, oxygen absorption, and dehydroxylation reactions occurs, which gives rise to a broad exotherm on the d.t.a, curve. The main products (for static heating condi- tions) are an oxyamphibole at 350-800 ~ C, and a spinel, hematite, a pyroxene, and X-ray amorphous material at 800-1100 ~ C. Silica crystallizes as cristobalite at 1100-1350 ~ C, and as tridymite at 1450 ~ C. Most of the products in either neutral or oxidizing atmospheres are formed topotactically. The mechanisms and rates of the reactions are discussed, and the problem of determining the chemically com- bined water in amosite and other minerals of similar composition is considered. MOSITE is the fibrous variety of the monoclinic amphibole, grunerite.
    [Show full text]
  • UNIVERS·I-TY of R~1Nni~S;91;A>,:O- ;;.' ~ I ,{-""
    L. This document is made available electronically by the Minnesota Legislative Reference Library I < I { as part of an ongoing digital archiving project. http://www.leg.state.mn.us/lrl/lrl.asp t .~ ,. I ! I I f . ) . l , I MINNESOTA -POLLIJTION CONTROL N,ENCY i ( l_ ':.. ! l I i I 1"-v_-- . COMMENTS ON AsBESTIFORM AND FIBROUS I . I ( MINERAL FRAGMENTS) RELATIVE TO RESERVE MINING COMPANY TACONITE DEPOSITS. l ' t,. ' I I-" . ..PREPARED . .. BY: . I j TIBOR ZoLTAIJ P1E1J PH,D,J PROFESSOR . .. i I : ;-~ OF MINERALOGY AND CRYSTALLOGRAPHY AND . I I ( JAMES H. STOUT, PH,D,J ASSOCIATE PROFESSOR ' _ 9F PETROL.OGY_ AND_ MINERA~?~?c'fi\1·( ·_. __ I f DEPARTMENT OF GEOLOGY AND,~§-i!·()'FllY:.SlCSJ UNIVERS·I-TY OF r~1NNi~s;91;A>,:o- ;;.' ~ I ,{-""- . UNDER MINNESOTA POLLUTION. CONTROL AGENCY i. l CONTRACT f-!o. 01649-50 d_,J I I I I <'.,., MARCH 24, 1976 MINNEAPOLIS, MINNESOTA .,· I 'I J I S:•; ~,._.\:, 1f Table of Contents PAGE Ab s tr a c t . .. ... ... 4 • • • • • o • • • • • • • • '° • • • l Preliminary repo·rt on: . A. Distinction between fibers of ·natural asbestos and cleavage fragments ...•.• ~·········· ......•.. 4 B. Mineralogical and petrological relationships between the Homestake and the Peter Mitchell Mines •.. ...................................... ,. • • ]_3 C. Evaluation of the NIOSH Homestake reports: (Reports I and I I) •.•.•••· ••.••••••••... ~ ........ ~ • 2 0 (I) J.D. Gillam, J.M. Dement, R.A. Lemen, J.K. Wagoner, V.E. Archer and H.P. Blejer: Mortality patterns among hard rock gold miners exposed to an asbestiform mineral. NIOSH, 1975 .. (II} J.M. Dement, R.D. Zumwalde and K .
    [Show full text]
  • University of California Santa Cruz Metastability Of
    UNIVERSITY OF CALIFORNIA SANTA CRUZ METASTABILITY OF TREMOLITE AT HIGH PRESSURES AND TEMPERATURES A thesis submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in EARTH SCIENCES by Jason Ott June 2020 The Thesis of Jason Ott is approved: ____________________________ Professor Quentin Williams, Chair ____________________________ Professor Elise Knittle ____________________________ Assistant Professor Alexander L. Ayzner ____________________________ Quentin Williams Acting Vice Provost and Dean of Graduate Studies Table of Contents List of Figures v List of Tables vii Abstract viii Acknowledgements and Dedication x 1. Raman Spectroscopic Constraints on Compression and Metastability 1 of the Amphibole Tremolite at High Pressures and Temperatures 1.1 Abstract 1 1.2 Introduction 2 1.3 Experimental Methods 3 1.4 Results and Discussion 11 1.4.1 Peak assignments 16 1.4.2 Hydroxyl stretch mode 17 1.4.3 Libration modes 18 1.4.4 Cation bonding environment 20 1.4.5 Mode-Grüneisen parameters 22 1.5 Implications 28 2. Metastable Preservation of C2/m Tremolite to 40 GPa: A High-Pressure 32 Single-Crystal X-ray Diffraction Study 2.1 Introduction 32 2.2 Experimental Methods 35 2.2.1 Ambient Conditions X-ray Diffraction 36 2.2.2 High-Pressure X-ray Diffraction 37 iii 2.3 Results and Discussion 39 2.3.1 Ambient Pressure Structural Refinement and 39 Unit Cell Parameters 2.3.2 Bulk Moduli, Equations of State, and Axial 45 Compressibilities 2.4 Implications 52 Bibliography 55 iv List of Figures Figure 1.1: The general structure of an amphibole mineral such as tremolite, 4 with monoclinic symmetry crystallizing in the C2/m space group.
    [Show full text]
  • Mineralogy and Metamorphism of the Stromatolite-Bearing Layers of the Biwabik Iron Formation
    MINERALOGY AND METAMORPHISM OF THE STROMATOLITE-BEARING LAYERS OF THE BIWABIK IRON FORMATION By Dan Foley A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Arts (Geology) at GUSTAVUS ADOLPHUS COLLEGE 2009 Mineralogy and Metamorphism of The Stromatolite-bearing Layers of The Biwabik Iron Formation By Dan Foley Under the supervision of Professor James Welsh ABSTRACT The 1.85 billion year old Biwabik Iron-formation of northeastern Minnesota contains some of the earliest forms of life on the planet, present in structures called stromatolites. Samples of the iron-formation were collected directly above and below stromatolite bearing horizons, to determine silicate mineralogy, so as to ultimately understand the effects of metamorphism on the stromatolites. Degree of metamorphism adjacent to the stromatolite horizons was found to range from late diagentic to moderate metamorphic grade. ACKNOWLEDGMENTS Special thanks should be given to the advisor of this thesis Professor James Welsh for his continued help and support. Thanks should also be given to the other professors of the Gustavus Adolphus Geology department. The author would also like to thank Professor Russell Shapiro whose research on stromatolites helped launch this work, and provided many of the samples. Thanks should also be extended to the mining companies who allowed us to gather samples and the workers of the Hibbing core library whose help in wading through the cores was greatly appreciated. Thanks should also be given to Macalester College for allowing us the use of their equipment and time, and specifically to Jeff Thole who’s help with the X-ray analyis is greatly appreciated.
    [Show full text]