Petrographic analysis

Seam correlations, measurements of rank and geologic history, interpretation of petroleum (qv) formation with coal deposits, prediction of coke properties, and detection of coal oxidation can be deterrnined from petrographic analysis. Constituents of seams can be observed over considerable distances, permitting the correlation of seam profiles in coal basins. Measurements of vitrinite reflectance within a seam permit mapping of variations in thermal and tectonic histories. Figure 2 indicates the relationship of vitrinite reflectance to maximum temperatures and effective heating time in the seam (11,15). 

A variety of instmmental techniques may be used to determine mineral content. Typically the coal sample is prepared by low temperature ashing to remove the organic material. Then one or more of the techniques of x-ray diffraction, infrared spectroscopy, differential thermal analysis, electron microscopy, and petrographic analysis may be employed (7). 

This investigation relied on petrographic analysis of polished sections using reflected light and the scanning electron microscopy (SEM) and electron microprobe (EPMA) analyses to identify minerals and to document the distribution of gold. The mineralized zone is coincident with a distinct bleached alteration zone that contains fine- to coarse-grained, subhedral arsenopyrite and pyrite in quartz-carbonate veins. 

Berry, W.F. Cole, D.L. Preparation and Polishing of Coal and Coke for Petrographic Analysis. Bituminous Coal Research Inc., Pennsylvania, 1965. 

All coals submitted to BCR for petrographic analysis are routinely checked for oxidation by comparing as-received analytical results with the established fresh coal R -volatile matter curve shown in Figure 1. Coals falling within reasonable limits of this correlation line (within Sy = 2.3%) are accepted as unoxidized all others are considered oxidized. 

Briquets prepared at BCR for petrographic analysis are maintained in a desiccator for an extended period prior to microscopic analysis. Specific high moisture coals have been analyzed for reflectance at regular intervals following their insertion in the desiccating atmosphere under these conditions of continued desiccation, reflectance remained relatively constant. 

Petrographic analysis was undertaken for almost all 225 samples and an additional 100 samples from the same pottery groups. The thin section slides were examined through a petrographic polarizing microscope (Nikon Labophot-Pol and Zeiss [for photography] models were used). 

The following section focuses on the variability of the clay bodies or pastes of the glazed ceramics previously characterized by LA-ICP-MS and LA-TOF-ICP-MS. The purpose of this study is to compare the variation in the ceramic pastes with the different glaze decorative technologies through time. The variability in the ceramic pastes will be characterized through instrumental neutron activation analysis (INAA) and petrographic analysis. 

Petrographic analysis was conducted of a sample of sherds from Groups 1, 2, and 3, of the INAA paste composition groups. The petrographic study was conducted for the purpose of comparing the current INAA analysis to previous petrographic studies of Early Islamic ceramics (33). 

Although the characterization of coal macerals on the basis of their fluorescence spectra is a recent innovation, it has already proven to be an excellent fingerprinting tool for the various macerals. In some cases, it is even more sensitive than normal petrographic analysis. The initial results of fluorescence spectral studies show that the various fluorescent macerals in single coals can be statistically discriminated on the basis of their spectral parameters and that even varieties of a single maceral type can be distinguished. Although the spectra obtained at this time are rather broad and not suitable for chemical structure analysis, the potential for structural analysis exists and may be realized with improvements in instrumentation. 

Petrographic analysis (DMMF Volume %) PSOC-2 PSOC-858... 

Part of this data in Table II is a series of British maceral concentrates. The Woolley Wheatly Lime sample is 93% fusinite while the Teversal Dunsil concentrate is 80% semifusinite with 13% fusinite. The Aldwarke Silkstone sample contains 43% semifu-sinite and 43% fusinite. The petrographic analysis of PSOC-2 reveals nearly equivalent amounts of fusinite, semifusinite, micrinite, and macrinite (6.8, 8.1, 7.5 and 8.5% respectively in the whole coal) while PSOC-858 contains primarily semifusinite as the inertinite. The differences in faH values for these iner-tinite samples are greater than the experimental error and these differences suggest that NMR techniques may be useful in characterizing the chemical structural differences between inertinite macerals. 

Petrographic analysis of the separated macerals, density determinations, and elemental analyses were performed at Argonne National Laboratories. The ash content of these samples is less than 1%. The oxygen levels reported here are obtained by difference. Computer correlations of the resulting parameters were done using the Statistical Analysis System on the VS/CMS system at the ER E-Linden site. Linear-regression analyses are also performed with that system. In the correlation plots which follow, samples will be identified by coal rank and maceral group. 

This work was performed under the auspices of the Office of Basic Energy Sciences, Division of Chemical Sciences, U.S. DOE under contract W-31-109-ENG-38. The authors thank K.L. Stock for the maceral separations, G.R. Dyrkacz for the petrographic analysis and helpful discussion, and VI. Spackman, Penn. State University for choosing and providing the coal samples. 

Table II. Petrographic Analysis of Maceral Concentrates from PSOC-828 and PSOC-1103 Coals.

Alginites were obtained from selected Permo-Carboniferous torbanites (i.e. algal-rich coals) which, upon petrographic analysis, were found to be rich in the required component. No concentration steps were required for samples used in this work as small blocks were selected in which the initial alginite concentrations were adequate (see Table I). 

It is easier to analyze quartz petrographically if the sample has been cleaned up by dissolving the non-quartz minerals in hot phosphoric acid. Petrographic analysis can be used to check the phosphoric acid residue produced in the N. A. Talvitie (45) method for the gravimetric examination of quartz. If the residue is not examined petrographically, the reported results may be high. 

Sample Proximate analysis (d.b.%) Ultimate analysis (d.a.f.%) C/ XH (d.b.%) Petrographic analysis Calorific value (kcal/kg)... 

Neutron activation and petrographic analysis of late medieval Spanish pottery from the major Spanish production centers of Seville, Granada, Patema-Manises, Barcelona, and Talavera-Puente allowed progress to be made in uniquely characterizing these production centers (5-7). Efforts to identify different Mexican majolica productions petrographically have been unsuccessful, and an attempt at chemical characterization by directly coupled plasma-optical emission spectroscopy was later determined to have been flawed by problems encountered with the dissolution of the ceramic samples... 

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