Phase Relations in the System Cao-Feox-Sio2 in H20-CO2 Mixtures 239

Total Page:16

File Type:pdf, Size:1020Kb

Phase Relations in the System Cao-Feox-Sio2 in H20-CO2 Mixtures 239 J. Japan. Assoc. Min. Petr. Econ. Geol. 73, 231-240, 1978 PHASE RELATIONS IN THE SYSTEM CaO-FeOX SiO2 IN H20-CO2 MIXTURES TETSUYA SHOJI Department of Mineral Development Engineering, The University of Tokyo The phase relations among calcite, wollastonite , ferrobustamite, andradite, heden- bergite, magnetite and quartz in H2O-CO2 mixtures have been estimated on the basis of previous work in the systems CaO-SiOa-CO, and CaO-Fe01 SiO2-O2. The upper limit of COs content of the condition favorable to the formation of skarn involving andradite and/or hedenbergite is restricted by the following reactions: (6) andradite+CO2 =calcite+magnetite+quartz+O2, (8) hedenbergite+CO2+O2=calcite+magnetite+quartz. From the andradite and hedenbergite fields, the skarn consisting of these minerals is inferred to be formed in H2O-CO2 fluids containing less 30 mole % CO2 at 500•Ž , and 0.5 mole % at 300•Ž, respectively. When ferrobustamite is stable, the phase relations are more complex. The above mentioned values, however, are independent on the stability of ferrobustamite. INTRODUCTION plot regardless CO, (Fig. 1), and listed in Table 1 with their abbreviations and molar Grandite garnet and/or chnopyroxene volumes calculated from the data complied of diopside-hedenbergiteseries are the most by Strunz (1970) and Yamanaka et al. (1977). important minerals which characterize the skarn-type ore deposits. They frequently Table 1. List of minerals. contain a considerable amount of iron. Besidesthem, the ore deposits of this type are usually composed of calcite, magnetite and quartz with sulfidesand oxides as ore minerals. For this reason, the phase rela tions among calcite, andradite, hedenbergite, * Calculated fron the data compiled by Strunz (1970). magnetite and quartz should indicate the except ferrobustamite (Yamanakaet al., 1977). favorable conditions of formation of ore bearing skarn. SOME STABLE REACTIONS IN THE SYSTEM Ca-Fe-Si-C-O AND RELA In this paper, the writer tries to estimate quantitatively the phase relations TIONSHIP AMONG THEM in the system CaO-FeOBSiO2 under the Fig. 2 shows the schematic, isobaric T fluidscomposed of water and carbon dioxide, f co, relations among calcite, andradite, on the basis of previous studies of the system hedenbergite and quartz under a controlled CaO-SiO2-CO2and CaO-FeORSiO2-O2. oxygen fugacity. In this diagram, there Compositions of phases considered in are apparently four invariant points and this paper are shown on a CaO-FeOx-SiO2 eleven univariant curves. These univariant (Manuscript received July 3, 1978) 232 Tetsuya Shoji curves are equilibirum boundaries for the reactions listed in Table 2. These reactions are combined one another as follows: Reaction(2)=1/2{9•EReaction(3) -Reaction (1)} (1) Reaction(3)=1/9{Reaction(1) +2• Reaction (2)} (2) Reaction(4)=1/3{Reaction(2) -Reaction(1)} (3) =1/2(3• Reaction(3) -Reaction (1)} Fig. 1. Compositions of crystalline phases in the Reaction(6)=9{Reaction(5) system Ca-Fe-Si-C-O projected on the -Reaction(1)} (4) CaO-FeOx SiO2 plane. Reaction(7)=Reaction(6)-Reaction(2) (5) +9•EReaction(5)} (6) Reaction(8)=1/3(Reaction(2)-Reaction (1) =1/3(Reaction(2)+Reaction(6)} Fig 2. Schematic analysis of phase relations in the system CaO-FeO-Fe2O3- SiO2-CO2 as a function of CO3 fugacity and temperature. Numerals correspond to the number of reaction (see Table 2). Capital letters in circles show isobaric, f02-defined invariant points (see Table 4). Abbreviations are shown in Table 1 and Fig. 1. Phase Relations in the System. CaO-FeOx-SiO2 in H2O-CO2 Mixtures 233 Table 2. Volume changes, enthalpy changes and entropy changes of some stable reactions in the system CaO-FeO-Fe202-Si02-C027% (at atmospheric pressure). * Gu=Gustafson (1974), Gw=Greenwood(1967), H-T=Harker and Tuttle (1956), K=Kurshakova (1971a,b), L=Liou (1974), S1=Shoji (1976b), S2=Shoji (1977), T-L=Taylor and Liou (1978) Reaction(9)=Reaction(3)-Reaction(5) (7) REACTIONS (1) TO (4) =1/9 {2•EReaction(2)-Reaction(6)} At first, let us consider the stability Reaction (10) relations among wollastonite, andradite, =2{Reaction(5)-Reaction(3)} (8) hedenbergite, magnetite and quartz. Fig. = Reaction(3)+2•EReaction (9) Reaction(11)=1/3{2•EReaction(1) +Reaction (7)} (9) Equations (1) to (9) mean that the number of independent reactions is three. Accord ingly, if three equilibrium boundaries among them, for example Reactions (1), (2) and (5), have been already determined, the other reactions can be calculated by the thermodynamic procedure which is derived from the reaction isobar of van't Hoff (Shoji, 1976b), Fig. 3. Schematic analysis of phase relations at •¬. On the estimation, Lewis' rule (ideal isobaric invariant point I, where the mixing of fluids) has been assumed, and assemblage wollastonite-andradite-heden- bergite-magnetite-quartz is stable. Solid fugacitydata of carbon dioxide and oxygen, lines represent the isobaric univariant except that of the Pb-PbO buffer (see phase relations, and dotted lines buffer Appendix), have been taken from Me,7ni curves. Numerals correspond to the num ber of reaction (see Table 2). Abbrevi- (1971)and Huebner (1971), respectively. ations are shown in Table 1. NNO and FMQ represent the Ni-NiO buffer and the fayalite-magnetite-quartz one, respec tively. 234 Tetsuya Shoji 3 shows the schematic, isobaric fo2-T rela This line is not necessarily inconsistent with tions in the system Ca-Fe-Si-O. In this the results of Iypmago$a (1971a, b). diagram, there are one invariant point and From this line, the equilibrium constant four univariant curves. The univariant of Reaction (2) is as follows: curves are equilibrium boundaries for Reactions (1) to (4). Equations (1) to (4) mean that the number of independent reactions is two. Phase relations in the system have been investigated by Rypma- •¬ The equilibrium boundary for Reaction EP Ba (1970,1971a, b), „K„…„‚‡V„p„{„€„Ž„p „y „@„Ž„u„„„y„ƒ„‘„~ (3) was determined by I ypmat oBa (1970, (1974), Gustafson (1974) and Liou (1974), 1971a), and by Liou (1974). Rypmaspa using solid phase oxygen buffers. The (1971a) stated that at 1000 bars Pffuid the equilibrium boundary for Reaction (1) was assemblage andradite-quartz is stable above determined by Gustafson (1974). The ex an oxygen fugacity of 10-13 bar at 800•Ž, periments were carried out between 500 and 10-20 bar at 500•Ž. On the contrary, bars and 3000 bars. The enthalpy and Liou (1974) concluded that at 2000 bars entropy changes, and equilibrium constant of Reaction (1) were calculated by Shoji (1977) (Table 1). The equilibrium boundary for Reaction (2) was determined by KypmanoBa (1971a, b), and by Gustafson (1974). IfiypinanoBa (1971b) stated that at 1000 bars Pflnid hedenbergite is stable below an oxygen fugacity of 10-14 bar at 750•Ž and 10-23 bar at 400•Ž. On the contrary, Gustafson (1974) concluded that at 2000 bars Pflnid hedenbergite is stable below an f o, of 10-13 bar at 800•Ž and 10-28 bar at 400•Ž. Both of the conclusions do not agree with each other at the low temperature. The data of their experiments, however, are ap proximately coincident with each other, as shown in Fig. 4, which represents a {2 ln fo2+‡™Vs(pf-1)/RT}vs. 1000/T plot of their results. The low temperature experiments performed by KypmanoBa (1971a, b) seem to have not been demonstrated as equilibrium, because the assemblage an Fig. 4. A (2 ln fo2+‡™Vs (iii-1)/RT) vs. 1000/T dradite-hedenbergite-magnetite-quartz was plot of the experimental data on Reac synthesized at 400°C within a wide fo, tion (2) reported by lcypmazoaa (1971a, b) and Gustafson (1974). Open symbols range. The straight line in Fig. 4 has been indicate reaction to andradite-magnetite- drawn for the data of Gustafson (1974). quartz; closed symbols to hedenbergite. Phase Relations in the System CaO-FeOx-SiO2 in H2O-C02 Mixtures 235 Pfluid this assemblage is stable above an fo, of 10-is bar at 800•Ž, and 10-26 bar at 500•Ž. Both of the conclusions do not agree with each other at the low tem perature. Liou (1974) suggested that the experiments performed by I£ypma iosa (1970, 1971a) had not been successfully demonstrated as equilibrium because of starting materials, run duration and experi mental methods. Fig. 5 shows a {1/2 In fo2 +‡™Vs(Pf-1)/RT}vs. 1000/T plot of their experimental results. The solid line in Fig. 5 have been drawn for the data of Liou (1974). From the line, the enthalpy and Fig. 5. A{1/2 ln fo2+‡™Vs(pf-1)/RT}vs. 1000/ entropy changes of Reaction (3) are calcu- T plot of the experimental data on Re lated to be 86.1 kcal and 52.5 cal.deg-1, action (3) reported by Kypmaxoea (1970, respectively. On the other hand, the 1971a) and Liou (1974). Open symbols indicate reaction to andraite-quartz; Gustafson's (1974) results suggest that closed symbols to wollastonite (or ferro- the enthalpy and entropy changes of bustamite ?)-hedenbergite. Reaction (3) are 71.5 kcal and 38.0 cal.deg-1, respectively (Table 2). These values have demonstrated as equilibrium. For this been calculated using equation (2). The reason, the writer believes that the values dashed line in Fig. 5 shows the calculated obtained from the results of Gustafson equilibrium boundary for Reaction (3). (1974)are more accurate than those on the The dashed line is not necessarily incon- results of I£ypniagosa (1970, 1971a) and sistent with the results of Kypluaaosa (1970, Liou (1974)*. 1971a), while it does not agree with the The enthalpy and entropy changes of results of Liou (1974).
Recommended publications
  • The Hydrous Component in Andradite Garnet
    American Mineralogist, Volume 83, pages 835±840, 1998 The hydrous component in andradite garnet GEORG AMTHAUER* AND GEORGE R. ROSSMAN² Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, U.S.A. ABSTRACT Twenty-two andradite samples from a variety of geological environments and two syn- thetic hydroandradite samples were studied by Fourier transform IR spectroscopy. Their 2 spectra show that H enters andradite in the form of OH . Amounts up to 6 wt% H2O occur in these samples; those from low-temperature formations contain the most OH2. Some 42 ↔ 42 features in the absorption spectra indicate the hydrogarnet substitution (SiO4) (O4H4) whereas others indicate additional types of OH2 incorporation. The complexity of the spectra due to multi-site distribution of OH2 increases with increasing complexity of the garnet composition. 42 ↔ 42 INTRODUCTION tution (O4H4) (SiO4) . This observation has been Systematic studies have shown that hydroxide is a con®rmed by XRD of a hydrous andradite with a Si de- common minor component of grossular and pyrope-al- ®ciency of about 50%, and a high OH content (Arm- mandine-spessartite garnets (Aines and Rossman 1985; bruster 1995). The structure of this particular sample with Rossman and Aines 1991). Comparable surveys of an- space group Ia3d is composed of disordered microdo- dradite garnet have not been previously presented. Sev- mains containing (SiO4) and (O4H4) tetrahedral units. eral reports indicate that appreciable amounts of OH2 can The aim of the present investigation was to perform a be incorporated in both natural and synthetic andradite- Fourier transform infrared (FTIR) study on different sam- rich garnet (Flint et al.
    [Show full text]
  • Washington State Minerals Checklist
    Division of Geology and Earth Resources MS 47007; Olympia, WA 98504-7007 Washington State 360-902-1450; 360-902-1785 fax E-mail: [email protected] Website: http://www.dnr.wa.gov/geology Minerals Checklist Note: Mineral names in parentheses are the preferred species names. Compiled by Raymond Lasmanis o Acanthite o Arsenopalladinite o Bustamite o Clinohumite o Enstatite o Harmotome o Actinolite o Arsenopyrite o Bytownite o Clinoptilolite o Epidesmine (Stilbite) o Hastingsite o Adularia o Arsenosulvanite (Plagioclase) o Clinozoisite o Epidote o Hausmannite (Orthoclase) o Arsenpolybasite o Cairngorm (Quartz) o Cobaltite o Epistilbite o Hedenbergite o Aegirine o Astrophyllite o Calamine o Cochromite o Epsomite o Hedleyite o Aenigmatite o Atacamite (Hemimorphite) o Coffinite o Erionite o Hematite o Aeschynite o Atokite o Calaverite o Columbite o Erythrite o Hemimorphite o Agardite-Y o Augite o Calciohilairite (Ferrocolumbite) o Euchroite o Hercynite o Agate (Quartz) o Aurostibite o Calcite, see also o Conichalcite o Euxenite o Hessite o Aguilarite o Austinite Manganocalcite o Connellite o Euxenite-Y o Heulandite o Aktashite o Onyx o Copiapite o o Autunite o Fairchildite Hexahydrite o Alabandite o Caledonite o Copper o o Awaruite o Famatinite Hibschite o Albite o Cancrinite o Copper-zinc o o Axinite group o Fayalite Hillebrandite o Algodonite o Carnelian (Quartz) o Coquandite o o Azurite o Feldspar group Hisingerite o Allanite o Cassiterite o Cordierite o o Barite o Ferberite Hongshiite o Allanite-Ce o Catapleiite o Corrensite o o Bastnäsite
    [Show full text]
  • Mid-Infrared Optical Constants of Clinopyroxene and Orthoclase Derived from Oriented Single-Crystal Reflectance Spectra
    American Mineralogist, Volume 99, pages 1942–1955, 2014 Mid-infrared optical constants of clinopyroxene and orthoclase derived from oriented single-crystal reflectance spectra JESSICA A. ARNOLD1,*, TIMOTHY D. GLOTCH1 AND ANNA M. PLONKA1 1Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, U.S.A. ABSTRACT We have determined the mid-IR optical constants of one alkali feldspar and four pyroxene compo- sitions in the range of 250–4000 cm–1. Measured reflectance spectra of oriented single crystals were iteratively fit to modeled spectra derived from classical dispersion analysis. We present the real and imaginary indices of refraction (n and k) along with the oscillator parameters with which they were modeled. While materials of orthorhombic symmetry and higher are well covered by the current literature, optical constants have been derived for only a handful of geologically relevant monoclinic materials, including gypsum and orthoclase. Two input parameters that go into radiative transfer models, the scattering phase function and the single scattering albedo, are functions of a material’s optical constants. Pyroxene is a common rock-forming mineral group in terrestrial bodies as well as meteorites and is also detected in cosmic dust. Hence, having a set of pyroxene optical constants will provide additional details about the composition of Solar System bodies and circumstellar materials. We follow the method of Mayerhöfer et al. (2010), which is based on the Berreman 4 × 4 matrix formulation. This approach provides a consistent way to calculate the reflectance coefficients in low- symmetry cases. Additionally, while many models assume normal incidence to simplify the dispersion relations, this more general model applies to reflectance spectra collected at non-normal incidence.
    [Show full text]
  • Mineral Collecting Sites in North Carolina by W
    .'.' .., Mineral Collecting Sites in North Carolina By W. F. Wilson and B. J. McKenzie RUTILE GUMMITE IN GARNET RUBY CORUNDUM GOLD TORBERNITE GARNET IN MICA ANATASE RUTILE AJTUNITE AND TORBERNITE THULITE AND PYRITE MONAZITE EMERALD CUPRITE SMOKY QUARTZ ZIRCON TORBERNITE ~/ UBRAR'l USE ONLV ,~O NOT REMOVE. fROM LIBRARY N. C. GEOLOGICAL SUHVEY Information Circular 24 Mineral Collecting Sites in North Carolina By W. F. Wilson and B. J. McKenzie Raleigh 1978 Second Printing 1980. Additional copies of this publication may be obtained from: North CarOlina Department of Natural Resources and Community Development Geological Survey Section P. O. Box 27687 ~ Raleigh. N. C. 27611 1823 --~- GEOLOGICAL SURVEY SECTION The Geological Survey Section shall, by law"...make such exami­ nation, survey, and mapping of the geology, mineralogy, and topo­ graphy of the state, including their industrial and economic utilization as it may consider necessary." In carrying out its duties under this law, the section promotes the wise conservation and use of mineral resources by industry, commerce, agriculture, and other governmental agencies for the general welfare of the citizens of North Carolina. The Section conducts a number of basic and applied research projects in environmental resource planning, mineral resource explora­ tion, mineral statistics, and systematic geologic mapping. Services constitute a major portion ofthe Sections's activities and include identi­ fying rock and mineral samples submitted by the citizens of the state and providing consulting services and specially prepared reports to other agencies that require geological information. The Geological Survey Section publishes results of research in a series of Bulletins, Economic Papers, Information Circulars, Educa­ tional Series, Geologic Maps, and Special Publications.
    [Show full text]
  • Reflective Index Reference Chart
    REFLECTIVE INDEX REFERENCE CHART FOR PRESIDIUM DUO TESTER (PDT) Reflective Index Refractive Reflective Index Refractive Reflective Index Refractive Gemstone on PDT/PRM Index Gemstone on PDT/PRM Index Gemstone on PDT/PRM Index Fluorite 16 - 18 1.434 - 1.434 Emerald 26 - 29 1.580 - 1.580 Corundum 34 - 43 1.762 - 1.770 Opal 17 - 19 1.450 - 1.450 Verdite 26 - 29 1.580 - 1.580 Idocrase 35 - 39 1.713 - 1.718 ? Glass 17 - 54 1.440 - 1.900 Brazilianite 27 - 32 1.602 - 1.621 Spinel 36 - 39 1.718 - 1.718 How does your Presidium tester Plastic 18 - 38 1.460 - 1.700 Rhodochrosite 27 - 48 1.597 - 1.817 TL Grossularite Garnet 36 - 40 1.720 - 1.720 Sodalite 19 - 21 1.483 - 1.483 Actinolite 28 - 33 1.614 - 1.642 Kyanite 36 - 41 1.716 - 1.731 work to get R.I. values? Lapis-lazuli 20 - 23 1.500 - 1.500 Nephrite 28 - 33 1.606 - 1.632 Rhodonite 37 - 41 1.730 - 1.740 Reflective indices developed by Presidium can Moldavite 20 - 23 1.500 - 1.500 Turquoise 28 - 34 1.610 - 1.650 TP Grossularite Garnet (Hessonite) 37 - 41 1.740 - 1.740 be matched in this table to the corresponding Obsidian 20 - 23 1.500 - 1.500 Topaz (Blue, White) 29 - 32 1.619 - 1.627 Chrysoberyl (Alexandrite) 38 - 42 1.746 - 1.755 common Refractive Index values to get the Calcite 20 - 35 1.486 - 1.658 Danburite 29 - 33 1.630 - 1.636 Pyrope Garnet 38 - 42 1.746 - 1.746 R.I value of the gemstone.
    [Show full text]
  • A Comparative Study of Jadeite, Omphacite and Kosmochlor Jades from Myanmar, and Suggestions for a Practical Nomenclature
    Feature Article A Comparative Study of Jadeite, Omphacite and Kosmochlor Jades from Myanmar, and Suggestions for a Practical Nomenclature Leander Franz, Tay Thye Sun, Henry A. Hänni, Christian de Capitani, Theerapongs Thanasuthipitak and Wilawan Atichat Jadeitite boulders from north-central Myanmar show a wide variability in texture and mineral content. This study gives an overview of the petrography of these rocks, and classiies them into ive different types: (1) jadeitites with kosmochlor and clinoamphibole, (2) jadeitites with clinoamphibole, (3) albite-bearing jadeitites, (4) almost pure jadeitites and (5) omphacitites. Their textures indicate that some of the assemblages formed syn-tectonically while those samples with decussate textures show no indication of a tectonic overprint. Backscattered electron images and electron microprobe analyses highlight the variable mineral chemistry of the samples. Their extensive chemical and textural inhomogeneity renders a classiication by common gemmological methods rather dificult. Although a deinitive classiication of such rocks is only possible using thin-section analysis, we demonstrate that a fast and non-destructive identiication as jadeite jade, kosmochlor jade or omphacite jade is possible using Raman and infrared spectroscopy, which gave results that were in accord with the microprobe analyses. Furthermore, current classiication schemes for jadeitites are reviewed. The Journal of Gemmology, 34(3), 2014, pp. 210–229, http://dx.doi.org/10.15506/JoG.2014.34.3.210 © 2014 The Gemmological Association of Great Britain Introduction simple. Jadeite jade is usually a green massive The word jade is derived from the Spanish phrase rock consisting of jadeite (NaAlSi2O6; see Ou Yang, for piedra de ijada (Foshag, 1957) or ‘loin stone’ 1999; Ou Yang and Li, 1999; Ou Yang and Qi, from its reputed use in curing ailments of the loins 2001).
    [Show full text]
  • 100 a Large Cleavage Piece of Pale Pink Bustamite from Franklin
    100 TH E AM ERICAN M I N ERA INGI ST A large cleavage piece of pale pink bustamite from Franklin Furnace kindly presented to the U. S. National Museum by Mr. R. B. Gage of Trenton, N. J., has the following optical properties: Optically-, 2V medium. a:1.667, P:1.678,ry: 1-680. Fragments lying on the most perfect cleavageshow the emergence of X out of the field and give variable but small extinction angles. Several specimens from Franklin Furnace that superficially resembledthe bustamite were examinedmicroscopically and proved to have optical properties much like those of the fowlerite variety of rhodonite, though with somewhat lower indices of refraction. Coxcriusrox: The bustamite from Franklin Furnace is a triclinic pyroxene, related to rhodonite. Chemically it contains nearly equal molecular proportions of CaO and MnO with CaO in stight excess. In optical properties it differs considerably from rhodon- ite. Out of ten specimens of bustamite and rhodonite, mostly from Franklin Furnace, that have been examined optically, two had properties very near those of the analyzed bustamite, six had properties near those of fowlerite, a variety of rhodonite, while one had properties about midway between the rhodonite and bustamite. ft, therefore, seemsprobable that bustamite is a subspecies of rhodonite with the approximate composition CaO.MnO.2SiOz. Further work to finally determine this is desir- able, and the authors would like to obtain samples of calciferous rhodonite and bustamite for optical study to determine to what extent replacement of MnO by CaO takes place in rhodonite. ALTERATION OF SILICATES BY SONSTADT'S SOLUTION T.
    [Show full text]
  • Andradite Ca3fe2 (Sio4)3 C 2001 Mineral Data Publishing, Version 1.2 ° Crystal Data: Cubic
    3+ Andradite Ca3Fe2 (SiO4)3 c 2001 Mineral Data Publishing, version 1.2 ° Crystal Data: Cubic. Point Group: 4=m 3 2=m: Commonly well-crystallized dodecahedra, trapezohedra, or combinations, to 5 cm. Also granular to massive. Physical Properties: Fracture: Uneven to conchoidal. Tenacity: Brittle. Hardness = 6.5{7 D(meas.) = 3.8{3.9 D(calc.) = 3.859 Optical Properties: Transparent to translucent. Color: Yellow, greenish yellow to emerald-green, dark green; brown, brownish red, brownish yellow; grayish black, black; may be sectored. Streak: White. Luster: Adamantine to resinous, dull. Optical Class: Isotropic; typically weakly anisotropic. n = 1.887 Cell Data: Space Group: Ia3d: a = 12.056 Z = 8 X-ray Powder Pattern: Synthetic. 2.696 (100), 3.015 (60), 1.6112 (60), 2.462 (45), 1.9564 (25), 1.6728 (25), 1.1195 (25) Chemistry: (1) (2) SiO2 34.91 35.47 TiO2 trace Al2O3 0.69 Fe2O3 30.40 31.42 MgO 0.58 CaO 33.20 33.11 H2O¡ 0.19 Total 99.97 100.00 3+ (1) Re·skovic stream, Serbia, Yugoslavia; corresponds to (Ca3:01Mg0:07)§=3:08(Fe1:94Al0:02)§=1:96 (Si2:95Al0:05)§=3:00O12: (2) Ca3Fe2(SiO4)3: Polymorphism & Series: Forms two series, with grossular, and with schorlomite. Mineral Group: Garnet group. Occurrence: In skarns from contact metamorphosed impure limestones or calcic igneous rocks; in chlorite schists and serpentinites; in alkalic igneous rocks, then typically titaniferous. Association: Vesuvianite, chlorite, epidote, spinel, calcite, dolomite, magnetite. Distribution: Widespread; ¯ne examples from; in Italy, at Frascati, Alban Hills, Lazio; the Val Malenco, Lombardy; the Ala Valley, Piedmont; and Larcinaz, Val d'Aosta.
    [Show full text]
  • List of Abbreviations
    List of Abbreviations Ab albite Cbz chabazite Fa fayalite Acm acmite Cc chalcocite Fac ferroactinolite Act actinolite Ccl chrysocolla Fcp ferrocarpholite Adr andradite Ccn cancrinite Fed ferroedenite Agt aegirine-augite Ccp chalcopyrite Flt fluorite Ak akermanite Cel celadonite Fo forsterite Alm almandine Cen clinoenstatite Fpa ferropargasite Aln allanite Cfs clinoferrosilite Fs ferrosilite ( ortho) Als aluminosilicate Chl chlorite Fst fassite Am amphibole Chn chondrodite Fts ferrotscher- An anorthite Chr chromite makite And andalusite Chu clinohumite Gbs gibbsite Anh anhydrite Cld chloritoid Ged gedrite Ank ankerite Cls celestite Gh gehlenite Anl analcite Cp carpholite Gln glaucophane Ann annite Cpx Ca clinopyroxene Glt glauconite Ant anatase Crd cordierite Gn galena Ap apatite ern carnegieite Gp gypsum Apo apophyllite Crn corundum Gr graphite Apy arsenopyrite Crs cristroballite Grs grossular Arf arfvedsonite Cs coesite Grt garnet Arg aragonite Cst cassiterite Gru grunerite Atg antigorite Ctl chrysotile Gt goethite Ath anthophyllite Cum cummingtonite Hbl hornblende Aug augite Cv covellite He hercynite Ax axinite Czo clinozoisite Hd hedenbergite Bhm boehmite Dg diginite Hem hematite Bn bornite Di diopside Hl halite Brc brucite Dia diamond Hs hastingsite Brk brookite Dol dolomite Hu humite Brl beryl Drv dravite Hul heulandite Brt barite Dsp diaspore Hyn haiiyne Bst bustamite Eck eckermannite Ill illite Bt biotite Ed edenite Ilm ilmenite Cal calcite Elb elbaite Jd jadeite Cam Ca clinoamphi- En enstatite ( ortho) Jh johannsenite bole Ep epidote
    [Show full text]
  • Andradite Skarn Garnet Records of Exceptionally Low Δ18o Values Within an Early Cretaceous Hydrothermal System, Sierra Nevada, CA
    Contributions to Mineralogy and Petrology (2019) 174:68 https://doi.org/10.1007/s00410-019-1602-6 ORIGINAL PAPER Andradite skarn garnet records of exceptionally low δ18O values within an Early Cretaceous hydrothermal system, Sierra Nevada, CA J. Ryan‑Davis1,2 · J. S. Lackey2 · M. Gevedon3 · J. D. Barnes3 · C‑T. A. Lee4 · K. Kitajima5 · J. W. Valley5 Received: 2 March 2019 / Accepted: 12 July 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Skarn garnets in the Mineral King roof pendant of the south–central Sierra Nevada within Sequoia National Park, Califor- nia, USA reveal variable fuid chemistry with a signifcant component of meteoric water during metasomatism in the Early Cretaceous Sierra Nevada Batholith. We focus on andradite garnet associated with Pb–Zn mineralization in the White Chief Mine. Laser fuorination oxygen isotope analyses of δ18O of garnet (δ18O(Grt)) from sites along the skarn show a large range of values (− 8.8 to + 4.6‰ VSMOW). Ion microprobe (SIMS) analyses elucidate that individual andradite crystals are strongly zoned in δ18O(Grt) (up to 7‰ of variation). Total rare-earth element concentrations (∑REE) across individual garnets show progressive depletion of skarn-forming fuids in these elements during garnet growth. These fndings support 18 18 a skarn model of earliest red high-δ O grandite garnet consistent with a magmatic-dominated equilibrium fuid (δ O(H2O) as high as ≈ + 8‰). Later, green andradite crystallized in equilibrium with a low-δ18O fuid indicating a signifcant infux 18 of meteoric fuid (δ O(H2O) ≈ − 6 to − 5‰), following a hiatus in garnet growth, associated with late-stage Pb–Zn miner- 18 18 alization.
    [Show full text]
  • The Anorthic Iron-Manganese Silicate, Pyroxmangite Has Now Been Recognisedfrom Four Localities: Iva (South Carolina); Tunaberg and Vester Silvberg, Sweden;Idaho
    PYROXMANGITE FROM INVERNESS-SHIRE, SCOTLAND . C. E. Trr,rov, Cambridge,England.. ' The anorthic iron-manganese silicate, pyroxmangite has now been recognisedfrom four localities: Iva (South Carolina); Tunaberg and Vester Silvberg, Sweden;Idaho. At the Swedish localities the mineral was originally described under the name of sobralite (Palmgren l9I7), but the comparative studies of Henderson and Glass (1936) have shown that sobralite has so closeagree- ment in optical characters with the previously described pyroxmangite that the identity of these two minerals can be regarded as established. The discovery of a further occurrence of pyroxmangite among the Lewisian rocks of Scotland has provided additional data on this inter- esting mineral. Frc. 1. Pyroxmangite-grunerite-garnet schist, Glen Beag, Glenelg, Inverness-shire. The constituents visible are pyroxmangite (most abundant), grunerite and magnetite. Spessartine-alamandine is present in adjacent portions of the slice. 26 diams. The Lewisian inlier of Glenelg, fnverness-shire contains among its para-gneissesa group of manganiferous eulysites and related grunerite schists (Tilley 1936), and from one outcrop of these latter rocks both pyroxmangite and rhodonite are now recorded. The pyroxmangite forms an important constituent of a manganiferous 720 IOURNAL MINEK LOGICAL SOCIETV OF AMEKICA 721 schist interbedded with a series of para-gneisses comprising biotite epidote gneisses,amphibole schists and lensesof limestone in the gorge of Glen Beag, Glenelg (1" sheet 71, GeologicalSurvey Scotland). The rock type with which the pyroxmangite is more intimately associated is a grunerite garnet schist carrying in placesveins of rhodonite up to 1 " in width. The constituent minerals of the principal band of rock are grunerite, manganiferous garnet, magnetite, pyroxmangite together with accessoryhedenbergite, iron hypersthene and pyrrhotite (Fig.
    [Show full text]
  • Andradite in Andradite Unusual Growth Zoning in Beryl
    Editor Nathan Renfro Contributing Editors Elise A. Skalwold and John I. Koivula Andradite in Andradite ity, but size was not what made it special. As shown in fig- Recently we had the opportunity to examine a dramatic ure 1, close examination of one of the polished crystal faces iridescent andradite fashioned by Falk Burger (Hard Works, revealed a bright reddish orange “hot spot” in the center, Tucson, Arizona) from a crystal originating from the caused by an iridescent inclusion of andradite with a dif- Tenkawa area of Nara Prefecture in Japan. Known as “rain- ferent crystallographic orientation than its host. As seen bow” andradite, this material was previously reported in in figure 2, the inclusion’s different orientation caused the iridescence of the rhomb-shaped “hot spot” to appear and Gems & Gemology (T. Hainschwang and F. Notari, “The cause of iridescence in rainbow andradite from Nara, disappear as the light source was passed over the crystal’s Japan,” Winter 2006, pp. 248–258). The specimen was surface. To see the iridescence from both the host and in- unique for its genesis and optical phenomenon. clusion at the same time, two light sources from opposite Weighing 16.79 ct and measuring 15.41 × 13.86 × 10.49 directions must be used due to the different crystallo- mm, the andradite was very large for its species and local- graphic orientation of the host and inclusion. This elusive optical phenomenon made this Japanese andradite crystal extremely interesting for any aspiring inclusionist. John I. Koivula Figure 1. This 16.79 ct Japanese andradite garnet GIA, Carlsbad exhibits a very unusual rhomb-shaped “hot spot” below the surface of one crystal face.
    [Show full text]