Petrographic

Within each chondrite class there are petrographic grades that relate to alteration processes that occurred within the meteorite parent body. The... 

Refraction Index. Refraction index is deterrnined with a petrographic microscope by submersing a sample in emersion oils of known refractive index. 

Characterization. Ceramic bodies are characterized by density, mass, and physical dimensions. Other common techniques employed in characterizing include x-ray diffraction (XRD) and electron or petrographic microscopy to determine crystal species, stmcture, and size (100). Microscopy (qv) can be used to determine chemical constitution, crystal morphology, and pore size and morphology as well. Mercury porosknetry and gas adsorption are used to characterize pore size, pore size distribution, and surface area (100). A variety of techniques can be employed to characterize bulk chemical composition and the physical characteristics of a powder (100,101). 

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). 

Euell ifi), (1991) contains a series of papers by leading researchers presented at the International Conference on Coal Stmcture and Reactivity chemical, physical, and petrographic aspects, Cambridge, UK, Sept. 5—7, 1990. 

Three West Virginia coals were supplied by the West Virgmia Geological Survey (WVGS). The particular coals were chosen on the basis of rank, petrographic composition, and mineral matter content The coals were limited to the bituminous rank since these coals are the most amenable to the NMP solvent extraction process and are mdigenous to the Appalachian region. Some of the coal characteristics are listed in Table 2. 

Krook, L. (1979). Sediment petrographical studies in northern Surinam, Ph.D. thesis. Free University. 

JOHANNSEN, A., 1918, Manual of Petrographic Methods, 2nd Edn New York, McGraw-Hill. 

Many drillings have been made for the purpose of the exploration of Kuroko deposits in the Green tuff region. A large number of petrographical and analytical data are available. Thus, it is possible to (1) assess the proportion of volcanic rocks that have suffered hydrothermal alteration, and (2) attempt a quantitative evaluation of the influence of hydrothermal alterations at back-arc basins on middle Miocene seawater chemistry. 

England, B.M. Mikka, R.A. Bagnall, B.J. Petrographic Characterization of Coal Using Automatic Image Analysis, J. Microscopy. 1979, 116, 329-336. 

Study of the Interrelationships among Chemical and Petrographic Variables of United States Coals, Tech. Rept. 9 to U.S. Department of Energy from Coal Research Section, Pennsylvania State University, Rept. FE-2030-TR 9, 1978. 

The chemical and petrographic properties of the twenty coals used in the hydrogenation experiments are shown in Tables II and III. Mineral matter was determined directly using a radio frequency low temperature plasma asher at medium power rating for approximately 48 h per coal. The volatile matter was corrected for the effects of the mineral matter by applying the equation used by Given et al (5). 

Table III Petrographic Composition of the Coals Used (Mineral Matter Free Basis)...

Table IV Petrographic Analyses and Ash Yield of Float/Sink Fractions...

Clarke, L. Storch, H.H., "Hydrogenation and Liquefaction of Coal, Part 2 - Effect of Petrographic Composition and Rank of Coal", Technical Paper 642, US Bureau of Mines, 1942. 

Figure 8. Relationship between conversion and petrographic components percent...

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