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1990 Fischer Standard study

Description: The purpose of this work is to develop a set of Titanium areal density standards for calibration and maintenance of the Fischer`s X-ray Fluorescence measurement system characterization curve program. The electron microprobe was calibrated for Titanium films on ceramic substrates using an existing set of laboratory standards (Quantity: 6 Range: 0.310 to 1.605). Fourteen source assemblies were measured and assigned values. These values are based on a mean calculation, of five separate readings, from best curve fit equations developed form the plot of the laboratory standards areal density (Source Measure) versus electron microprobe measurement (reading). The best fit equations were determined using the SAS General Linear Modeling (GLM) procedure. Four separate best fit equations were evaluated (Linear, Quadratic, Cubic and Exponential). Areal density values for the Fischer Standards appear here ordered by best fit equation based on maximum R{sup 2}.
Date: September 12, 1990
Creator: Roubik, G.J.
Partner: UNT Libraries Government Documents Department

Experimental gun brightness measurements on a 300 kV CFEG

Description: Effective use of the ANL 300kV CFEG/AAEM requires a knowledge of the probe current and size distribution during operation. In most cases this can be calculated once basic parameters of the system are experimentally determined. Central to this is a determination of the source brightness of the Cold Field Emission Gun (CFEG) under standard operating conditions of the instrument. For the last ten years most probe calculations of CFEG`s have been done assuming a brightness parameter of {beta}{approximately}1{times}10{sup 9} A/cm{sup 2}/sterad{sup 2} at 100 kV, while few if any experimental values have been reported at 300 kV. In order to determine {beta}, and thus characterize the source, the authors have measured the probe size, current and convergence angles on the ANL AAEM and from this calculated the effective brightness as a function of operating conditions. They compute d{sub g} = 0.92 nm and effective source brightness for the system of {beta} = 8.6{times}10{sup 8} A/cm{sup 2}/sterad. A value which is within experimental errors of the commonly used parameter at 100 kV, but is less than the expected value of {approximately}4{times}10{sup 9} A/cm{sup 2}/sterad.
Date: January 1, 1998
Creator: Zaluzec, N.J. & Nicholls, A.
Partner: UNT Libraries Government Documents Department

Detailed petrographic descriptions and microprobe data for tertiary silicic volcanic rocks in drill hole USW G-1, Yucca Mountain, Nevada

Description: This report contains detailed petrographic descriptions of 74 thin sections from drill hole USW G-1 at Yucca Mountain, Nevada. These descriptions are keyed to the distinctions between devitrified, vitrophyre, vitric, and zeolitized intervals below the Topopah Spring Member repository horizon. The petrographic features of the zeolitized intervals down through the Crater Flat tuff, as well as the sorption properties determined from these intervals, suggest that these zeolite occurrences may each have comparable sorptive capability.
Date: December 1, 1985
Creator: Caporuscio, F.A.; Warren, R.G. & Broxton, D.E.
Partner: UNT Libraries Government Documents Department

An Electron Microprobe Determination of Microscopic Elemental Homogeneity of Hot-Cross-Rolled and High-Energy-Rate Forged 21Cr-6Ni-9Mn Steel

Description: Electron microprobe analysis shows that iron, manganese, and nickel are inhomogeneously distributed in hot-cross-rolled plate and high-energy-rate forgings of 21Cr-6Ni-9Mn steel but that chromium is homogeneously distributed. Increases in iron content correlate with decreases in manganese and nickel. Rolling and forging flow lines occur in regions with high iron and low manganese and nickel. High-energy-rate forging increases inhomogeneity. Inhomogeneities are suspected to exist in the original ingot, where they are given directionality by rolling and are enhanced by high-energy-rate forging. This report discusses this study.
Date: February 17, 1981
Creator: Mosley, W.C.
Partner: UNT Libraries Government Documents Department

The role of carbon and temperature in determining electrical conductivity of basins, crust and mantle. Progress report, July 1, 1992--December 31, 1992

Description: Initial phase was concentrated on improving electron microprobe techniques for carbon mapping of polished sections. Experiments were carried out on the utility of Au/Pd, Cr, and Ag coats; results shows that Cr and Ag gave good results. Observations were made on maps of carbon distribution in rocks; low magnification base maps consisting of a mosaic of BSE images were produced on the SEM, and traverses were plotted. The metamorphic rocks adjacent to the Denali fault were chosen for study.
Date: December 31, 1992
Creator: Mathez, E.
Partner: UNT Libraries Government Documents Department

Ultrafast scanning probe microscopy

Description: The authors have developed a general technique which combines the temporal resolution of ultrafast laser spectroscopy with the spatial resolution of scanned probe microscopy (SPM). Using this technique with scanning tunneling microscopy (STM), they have obtained simultaneous 2 ps time resolution and 50 {angstrom} spatial resolution. This improves the time resolution currently attainable with STM by nine orders of magnitude. The potential of this powerful technique for studying ultrafast dynamical phenomena on surfaces with atomic resolution is discussed.
Date: January 1, 1994
Creator: Botkin, D.; Weiss, S.; Ogletree, D. F.; Salmeron, M. & Chemla, D. S.
Partner: UNT Libraries Government Documents Department

Characterization of the Wymark CO2 Reservoir: A Natural Analog to Long-Term CO2 Storage at Weyburn

Description: Natural accumulations of CO{sub 2} occur in the Duperow and other Devonian strata on the western flank of the Williston Basin in lithologies very similar to those into which anthropogenic CO{sub 2} is being injected as part of an EOR program in the Weyburn-Midale pool. Previous workers have established the stratgraphic and petrographic similarities between the Duperow and Midale beds (Lake and Whittaker, 2004 and 2006). As the CO{sub 2} accumulations in the Devonian strata may be as old as 50 Ma, this similarity provides confidence in the efficacy of long-term geologic sequestration of CO{sub 2} in the Midale-Weyburn pool. Here we attempt to extend this comparison with whole rock and mineral chemistry using the same sample suite used by Lake and Whittaker. We provide XRD, XRF, and electron microprobe analysis of major constituent minerals along with extensive backscattered electron and x-ray imaging to identify trace phases and silicate minerals. LPNORM analysis is used to quantify modal concentrations of minerals species. Samples from depth intervals where CO{sub 2} has been observed are compared to those where CO{sub 2} was absent, with no systematic differences in mineral composition observed. Gas accumulation can be correlated with sample porosity. In particular gas-bearing samples from the Eastend region are more porous than the overlying gas-free samples. Silicate minerals are rare in the Duperow carbonates, never exceeding 3 wt%. As such, mineral trapping is precluded in these lithologies. The geochemical data presented here will be used for comparison with a similar geochemical-mineralogical study of the Midale (Durocher et al., 2003) in a subsequent report.
Date: November 22, 2010
Creator: Ryerson, F & Johnson, J
Partner: UNT Libraries Government Documents Department

Toxic substances from coal combustion - forms of occurrence analyses. Semi-annual report, April 30, 1996--November 1, 1996

Description: The overall objective of this project is to provide analytical support for the Physical Sciences, Inc. (PSI) effort being performed under DOE Contract No. DE-AC22-95101 and entitled `` Toxic Substances from Coal Combustion - A Comprehensive Assessment``. The Pittsburgh Elkhorn/Hazard, and Illinois No. 6 program coals have been examined to determine the mode of occurrence of selected trace elements using scanning electron microscopy, microprobe analysis, and experimental leaching procedures. Preliminary microprobe data indicates that the arsenic content of pyrite grains in the Illinois No. 6 (0.0-0.027 ppm As) and Pittsburgh (0.0-0.080 ppm As) coals is similar. Pyrite grains observed in the Elkhorn/Hazard coal generally have arsenic concentrations (0.0-0.272 wt. %As) that are slightly higher than those of the Pittsburgh or Illinois No. 6 coals. One pyrite grain observed in the Elkhorn/Hazard coal contained much higher levels of arsenic (approximately 2 wt. % As). Preliminary microprobe analyses and data from leaching experiments indicate the association of arsenic with pyrite in the Pittsburgh and Illinois No. 6 coals. Leaching data for arsenic in the Elkhorn/Hazard coal, in contrast, is inconclusive and additional data are needed before a definite determination can be made.
Date: December 1, 1996
Creator: Crowley, S.S.; Palmer, C.A.; Kolker, A.; Finkelman, R.B. & Kolb, K.C.
Partner: UNT Libraries Government Documents Department

Characterization of U-6Nb ingots produced via the electron beam cold hearth refining process

Description: A study was undertaken at Lawrence Livermore National Laboratory to characterize uranium, 6% niobium ingots produced via electron beam melting, hearth refining and continuous casting and to compare this material with conventional VIM/skull melt/VAR material. Samples of both the ingot and feed material were analyzed for niobium and trace metallic elements, carbon, oxygen and nitrogen. This material was also inspected metallographically and via microprobe analysis.
Date: November 14, 1997
Creator: McKoon, R.H.
Partner: UNT Libraries Government Documents Department

TOXIC SUBSTANCES FROM COAL COMBUSTION-FORMS OF OCCURRENCE ANALYSES. INCLUDES SEMIANNUAL REPORT FOR MARCH 31, 1998.

Description: Detailed information on trace-element modes of occurrence in coal is essential to understanding and predicting trace-element transformations taking place during coal combustion. The USGS has developed quantitative and semi-quantitative methods for determining the mode of occurrence of trace elements in coal. This information is needed to generate predictive models for trace-element behavior, the ultimate goal of this integrated study. While the USGS has a relatively small part of the overall study, the results have direct bearing on the predictive equations being developed as the primary product of this program. The USGS procedure uses an iterative selective leaching protocol on whole coals in combination with a range of complementary studies. The sequence of leaching steps, and the intended results, are as follows: (1) exchangeable cations, and a fraction of the carbonate-hosted cations are removed by ammonium acetate; (2) cations primarily associated with carbonates and monosulfides such as galena, sphalerite and chalcopyrite are removed by hydrochloric acid; (3) silicate-associated cations are removed by hydrofluoric acid; and (4) elements associated with di-sulfides (pyrite and marcasite) are removed by nitric acid. The amount of an element leached by a given reagent is compared to concentrations of that element in the whole coal to obtain the fraction of an element having the indicated residence. Elements not leached by any of the four reagents may be present in the organic portions of the coal, or in insoluble phases such as zircon or titanium dioxides. Additionally, where mineral grains are completely encased by the organic matrix, these ''shielded'' grains may not be completely digested. Quantitative results are obtained by interpreting the leaching data together with the results obtained by complementary techniques such as electron microprobe analysis.
Date: September 30, 1998
Partner: UNT Libraries Government Documents Department

User oriented software system for electron microprobes

Description: A user-oriented software system for electron microprobes is described. The TASK automation program which provides instrument control and data collection is also capable of calling auxiliary programs which can provide quantitative data reduction, editing, plotting, summary, and statistical analysis capabilities. Qualitative analysis auxiliary capabilities include digital electronic scanning of the beam, mechanical scanning of the stage and the wavelength dispersive (WDS) spectrometers, identification of energy dispersive (EDS) peaks, low magnification x-ray mapping (which requires synchronous scanning of the spectrometers and the electron beam) and particle characterization. A disk operating system facilitates loading, exchanging, and saving of programs and data.
Date: January 1, 1979
Creator: Chambers, W.F. & Doyle, J.H.
Partner: UNT Libraries Government Documents Department

The form, distribution and mobility of arsenic in soilscontaminated by arsenic trioxide, at sites in southeast USA

Description: Soils from many industrial sites in southeastern USA arecontaminated with As because of the application of herbicide containingAs2O3. Among those contaminated sites, two industrial sites, FW and BH,which are currently active and of most serious environmental concerns,were selected to characterize the occurrence of As in the contaminatedsoils and to evaluate its environmental leachability. The soils are bothsandy loams with varying mineralogical and organic matter contents.Microwave-assisted acid digestion (EPA method 3051) of the contaminatedsoils indicated As levels of up to 325 mg/kg and 900 mg/kg (dry weightbasis) for FW and BH soils, respectively. However, bulk X-ray powderdiffraction (XRD) analysis failed to find any detectable As-bearingphases in either of the studied soil samples. Most of the soil As wasobserved by scanning electron microscopy, coupled with energy dispersiveX-ray spectroscopy (SEM/EDX), to be disseminated on the surfaces offine-grained soil particles in close association with Al and Fe. A fewAs-bearing particles were detected in BH soil using electron microprobeanalysis (EMPA). Synchrotron micro-XRD and X-ray absorption near-edgestructure (XANES) analyses indicated that these As-rich particles werepossibly phaunouxite, a mineral similar to calcium arsenate, which couldhave been formed by natural weathering after the application of As2O3.However, the scarcity of those particles eliminated them from playing anyimportant role in Assequestration.Synthetic acid rain sequential batchleaching experiments showed distinct As leaching behaviors of the twostudied soil samples: BH soil, which has the higher As content, showed aslow, steady release of As, while FW soil, with a lower As content,showed a much quicker release and lower overall retention of As uponleaching. Sequential chemical extraction experiments were carried outusing a simplified 4-step sequential chemical extraction procedure (SCEP)previously developed to characterize the fractionation of As and betterunderstand the different leaching behaviors of the two studied soils. Itwas shown that only about 50 percent of the total extractable As wasremoved by the first two extraction ...
Date: March 4, 2005
Creator: Yang, Li & Donahoe, Rona J.
Partner: UNT Libraries Government Documents Department

The role of carbon and temperature in determining electrical conductivity of basins, crust and mantle

Description: Initial phase was concentrated on improving electron microprobe techniques for carbon mapping of polished sections. Experiments were carried out on the utility of Au/Pd, Cr, and Ag coats; results shows that Cr and Ag gave good results. Observations were made on maps of carbon distribution in rocks; low magnification base maps consisting of a mosaic of BSE images were produced on the SEM, and traverses were plotted. The metamorphic rocks adjacent to the Denali fault were chosen for study.
Date: January 1, 1992
Creator: Mathez, E.
Partner: UNT Libraries Government Documents Department

The oxidation behavior of iron aluminides at 1300{degrees}C

Description: The oxidation behavior of iron-aluminum alloys, in air and oxygen, at 1300{degrees}C has been studied with particular emphasis on the time to loss of protectiveness with onset of breakaway attack. The role of alloy aluminum content between 8.4 and 15.8 w/o and of the addition of a reactive element, zirconium, up to 0.2 w/o, were examined. The periods over which the oxide scales remained protective were quantitatively correlated with aluminum depletion in the alloy substrate. Times to the onset of breakaway for Fe{sub 3}Al-Zr have been compared with those for commercial ODS FeCrAl alloys containing Y{sub 2}O{sub 3} (MA 956, PM 2000, ODM 751). Characterization of the oxidation of the Fe3Al-Zr alloys was undertaken using a range of surface analytical procedures, including x-ray diffraction, optical microscopy, scanning and scanning transmission electron microscopy with associated energy dispersive x-ray spectroscopy, and electron microprobe analysis.
Date: November 1, 1996
Creator: Bennett, M.J.; DeVan, J.H. & Tortorelli, P.F.
Partner: UNT Libraries Government Documents Department

Geochemistry and origin of regional dolomites. Final report

Description: The main goal of our research on dolomites has been to better understand the composition of the fluids and processes of the fluid-rock interaction responsible for the formation of massive dolostones occurring over regional scales within sedimentary sequences. Understanding the timing of dolomitization, the fluids responsible for the dolomitization and the timing of the development of porosity has major economic ramifications in that dolomites are major oil reservoirs often having better reservoir properties than associated limestones. Our approach has been to apply trace element, major element, petrographic, crystallographic, stable isotope and radiogenic isotope systems to test models for the origins of dolomites and to give information that may allow us to develop new models. Fluid compositions and processes are evaluated through the use of numerical models which we have developed showing the simultaneous evolution of the trace element and isotope systems during dolomitization. Our research has included the application of B, O, C, Sr, Nd and Pb isotope systematics and the trace elements Mn, Fe St, rare earth elements, Rb, Ba, U, Th, Pb, Zn, Na, Cl, F and SO{sub 4}{sup 2-}. Analyses are possible on individual cements or dolomite types using micro-sampling or microprobe techniques. The microprobe techniques used include synchrotron X-ray microprobe analysis at Brookhaven National Laboratory or electron microprobe at Stony Brook. Lack of a modern analogue for ancient massive dolostones has limited the application of the uniformitarian concept to developing models for the ancient regional dolostones. In addition it has not been possible to synthesize dolomite in the laboratory under conditions similar to the sedimentary or diagenetic possible environments in which the dolomites must have formed.
Date: May 1, 1995
Creator: Hanson, G.N. & Meyers, W.J.
Partner: UNT Libraries Government Documents Department

Geochemical similarities between volcanic units at Yucca Mountain and Pahute Mesa: evidence for a common magmatic origin for volcanic sequences that flank the Timber Mountain Caldera

Description: Chemical compositions have been determined for sanidine, plagioclase, biotite, and hornblende phenocrysts by electron microprobe for a comprehensive set of samples of Crater Flat Tuff and tuffs of Calico Hills. Most of these samples were obtained from drill holes at Yucca Mountain. Samples of tuffs and lavas of Area 20, obtained from locations at Pahute Mesa, have similarly been subjected to microprobe analysis. Complete modal petrography has been determined for all samples. Biotite and hornblende in the samples from both Yucca Mountain and Pahute Mesa have Fe-rich compositions that contract strikingly with Fe-poor compositions in the overlying Paintbrush Tuff and the underlying Lithic Ridge Tuff at Yucca Mountain. Each unit from Yucca Mountain has distinctive compositions for both sanidine and plagioclase that very closely match compositions for a corresponding unit identified within the lower, middle and upper portions of the Area 20 tuffs and lavas from Pahute Mesa. Each of these paired units probably originated from a common parental magma and was eruptd contemporaneously or nearly so. Each pair of units with matching phenocryst chemistries has a similar, but not identical set of petrographic characteristics. The petrographic differences, as well as small differences in phenocryst chemistry, result from a sonal distribution of phenocrysts within the parent magma chamber and eruption through earlier units that differ markedly between Yucca Mountain and Pahute Mesa.
Date: December 31, 1983
Creator: Warren, R.G.
Partner: UNT Libraries Government Documents Department

Analytical electron microscopy of bimetallic catalysts. Final report

Description: The report summarizes the accomplishments, publications, and reception of this program in the catalyst and microanalytical communities. Initially the research covered a wide range of catalysts, but later in the program, the author prepared and optimized a highly active catalyst for low-temperature NO abatement in fossil fuel power plants. During the course of the program, several innovations in microanalytical instrumentation and technique were developed specifically for analysis of catalytic nanoparticles. New designs for improved nanoparticle elemental sensitivity were proposed and accepted by the manufacture of Lehigh`s new VG /HB-603 analytical electron microscope. New tests for assessing elemental sensitivity have been devised and used to encourage the manufacturer to build the most sensitive analytical electron microscope in the world. Accomplishments summarized for the 1986--1990 period include: Quantitative measurements of noble metal distributions in alumina monoliths; Direct elemental imaging of small metal particles poisoned by sulfur: Analysis of surface species on Co/La/alumina catalyst; and Development of analytical electron microscopy methods. Accomplishments for the 1991--1993 period include: Catalytic testing facility for the electron microscopy lab; New scheme for immobilization of surface species for AEM analysis; and New method for electron probe microanalysis of porous materials. Accomplishments for the 1994--1998 period were: successful low-temperature NO reduction using a new Pt-Rh alloy catalyst; Composition size diagrams to identify active catalysts; Observation of phase separation in Pt-Rh at 300 C; Observation of surface segregation in Pt-rich nanoparticles; CO oxidation over Pt-Rh catalyst; Sulfur poisoning characteristics; Commercial development of NO catalysts; and Analysis of sub-1-nm particles in Pt-Re reforming catalysts.
Date: September 7, 1998
Creator: Lyman, C.E.
Partner: UNT Libraries Government Documents Department

Chemical variability of zeolites at a potential nuclear waste repository, Yucca Mountain, Nevada

Description: The compositions of clinoptilolites and their host tuffs have been examined by electron microprobe and x-ray fluorescence, respectively, to determine their variability at a potential nuclear waste repository, Yucca Mountain, Nevada. Because of their sorptive properties, these zeolites could provide important geologic barriers to radionuclide migration. Variations in clinoptilolite composition can strongly affect the mineral`s thermal and ion-exchange properties, thus influencing its behavior in the repository environment. Clinoptilolites and heulandites closest to the proposed repository have calcium-rich compositions (60 to 90 mol. % Ca) and silica-to-aluminum ratios that concentrate between 4.0 and 4.6. In contrast, clinoptilolites and their host tuffs deeper in the volcanic sequence have highly variable compositions that vary vertically and laterally. Deeper-occurring clinoptilolites in the eastern part of Yucca Mountain are characterized by calcic-potassic compositions and tend to become more calcium-rich with depth. Clinoptilolites at equivalent stratigraphic levels on the western side of Yucca Mountain have sodic-potassic compositions and tend to become more sodium-rich with depth. Despite their differences in exchangeable cation compositions these two deeper-occurring compositional suites have similar silica-to-aluminum ratios, concentrating between 4.4 and 5.0. The chemical variability of clinoptilolites and their host tuffs at Yucca Mountain suggest that their physical and chemical properties will also vary. Compositionally-dependent clinoptilolite properties important for repository performance assessment include expansion/contraction behavior, hydration/dehydration behavior, and ion-exchange properties.
Date: December 31, 1985
Creator: Broxton, D.E.
Partner: UNT Libraries Government Documents Department

A Scanning Auger Microprobe analysis of corrosion products associated with sulfate reducing bacteria

Description: A Scanning Auger Microprobe analysis was performed on the corrosion products of an austenitic AISI type 304 SS after a potentiostatic polarization of one volt for ten minutes in a modified Postgate`s C media containing sulfate reducing bacteria. The corrosion products were characterized and mapped in local regions where pitting was observed. A critical evaluation of the applicability of this technique for the examination of microbially influenced corrosion (MIC) is presented.
Date: March 1, 1995
Creator: Sadowski, R.A.; Chen, G.; Clayton, C.R.; Kearns, J.R.; Gillow, J.B. & Francis, A.J.
Partner: UNT Libraries Government Documents Department

Immobilization of AM-241, Formed Under Plutonium Metal Conversion into Monazite-Type Ceramics

Description: Lanthanum orthophosphate with the monazite structure was proposed on examinations as a suitable matrix for immobilization of future americium-containing liquid wastes, which could be formed in conversion of metallic plutonium into oxide at PA ''Mayak.'' Specimens of monazite non-active ceramics were fabricated from LaPOA powders obtained using a thin-film evaporator by either hot-pressing or cold-pressing and sintering at 900-1300 C. According to electron microprobe analysis (EMPA), scanning electron microscopy (SEM), and X-ray diffraction (XRD), which were used for characterization of produced samples, all specimens did not contain any phase other than the monoclinic monazite phase. Ceramics having the specific activity of Am-241 2.13 {center_dot}10{sup 7} Bq/g were prepared by only cold-pressing with subsequent sintering at 1300 C during 1 hour. The normalized leach rates of lanthanum and americium in distilled water at 90 C were less than 1.2. 10{sup 4} and 2.3 10{sup -4} g/m{sup 2} {center_dot} day, respectively.
Date: June 6, 2001
Creator: Aloy, A S; Kovarskaya, E N; Koltsova, T I; Samoylov, S E; Rovnyi, S I; Medvedev, G M et al.
Partner: UNT Libraries Government Documents Department

Bed material agglomeration during fluidized bed combustion. Technical progress report, 1 July, 1993--30 September, 1993

Description: Agglomerates formed in laboratory coal combustion tests were analyzed to determine the chemical and mineral reactions which lead to the cohesion of bed particles. Combustion tests were conducted at 75, 90, 100, and 120% theoretical air values. The test at 75% theoretical air resulted in the formation of bed agglomerates within 30 minutes. Agglomerates which formed at the lower theoretical air values were compared to unagglomerated bed samples by X-ray diffraction analyses. Polished thin sections of the agglomerates were made for optical and scanning electron microscopy. The results of these analyses indicate there were, in a broad sense, two types of mineralogic reactions which lead to the cohesion of bed particles in the agglomerates. One mechanism of cohesion resulted from the melting of bed particles to form a viscous material which bridged other bed particles. Based on the chemical composition of the glass (which resulted from the melt), this material was probably derived from aluminosilicate minerals in the sand bed or from clays within the coal. Because of the high iron content in these glasses (4 to 5 wt%), it is likely that iron pyrites in the coal were involved in fluxing reactions. In addition, MgO appears to be relatively high in the glasses. It is suspected that Ca-Mg carbonates (dolomite) from the bed sand are also involved in mineralogic reactions with the aluminosilicate melt. The second type of mineralogic reaction appears to be a reaction involving calcium and magnesium with other bed particles and with the aluminosilicate melt to form new mineral phases. Although the composition of these phases is somewhat variable, some resemble single-chain silicates or pyroxenes.
Date: November 1, 1993
Creator: Brown, R. C.; Dawson, M. R. & Noble, S. D.
Partner: UNT Libraries Government Documents Department