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M.-V. Wandless

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Specifically considers unusual minerals and geothermometric relations not previously covered. Equilibrium, if attained at all, during deposition of most sulfides was a transient event over a few tens of micrometers at most and was perturbed by rapid temperature and compositional changes of the circulating fluid. Two new minerals were found: one, a hydrated Zn, Fe hydroxy-chlorosulfate, and the other, a (Mn, Mg, Fe) hydroxide or hydroxy-hydrate. Both were formed at relatively low temperatures. Lizardite, starkeyite, and anatase were found for the first time in such an environment.-from Authors
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An important aspect of the petrographic description of coal is the characterization of coal quality, including chemical attributes. For geologic investigations, data on the concentrations, distribution, and modes of occurrence of minor and trace elements provide a basis for reconstructing the probable geochemical environment of the swamp material that was converted into peat, and the geochemical conditions that prevailed during and subsequent to coalification. We have been using electron (EPMA) and proton (PIXE) microprobe analytical methods to obtain data on the chemical characteristics of specific coal constituents in their original associations within coal samples. The present study is aimed at evaluation of...
Categories: Publication; Types: Citation
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The association of 34 elements with minerals found in coal was determined by a combination of analytical techniques on size and density fractions of low-temperature ash (LTA). Instrumental neutron activation analysis was used to determine the concentrations of the elements, and X-ray diffraction analysis, scanning electron microscopy, and scanning transmission electron microscopy were used to identify the minerals present in the LTA. The distribution of elemental and mineral concentrations in different size fractions was also determined. Between 35 and 60 weight percent of the LTA was composed of particles smaller than 2 mu m.
Categories: Publication; Types: Citation
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This breccia contains large lithic fragments of troctolite, norite and anorthosite. The mafic phases olivine, inverted pigeonite and augite fill interstitial areas between large plagioclases and appear to be cumulate phases with extensive adcumulus growth. Pyroxene homogeneity indicates that cation exchange during cooling was limited to approx 1 mm. Primary augite and pigeonite both contain 30 mu m-wide lamellae of the other along '001'. Pigeonite inverted to orthopyroxene without retaining any crystallographic orientation and subsequently exsolved fine lamellae of augite of (100). TEM profiles show an increase of approx 5% wollastonite in augite within 0.5 mu m of the interface, suggesting that short- range cation...
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