Pyrite morphology

The iron sulfides found intimately associated with fresh plant tissues in near surface sediments were in most cases classified as framboidal. In addition, irregular pyrite morphologies were identified deeper in the cores, infilling organic tissues that would be classified by coal petrographers as inertinite. 

Pyrite Morphology. Pyrite formed during early diagenesis in marsh sediments nas essentially two modes of occurrence, as small single crystals and as framboids (18). The processes that lead to one form or the other remain unclear. Euhedra may form by direct... 

Arora, H. S, J. B. Dixon, and L. R. Hossner. 1978. Pyrite morphology in lignitie coal and associated strata of east Texas. Soil Sci. 125 151-159. 

Zhang, Y. L., R. W. Blanchar, and R. D. Hammer. 1993. Composition and pyrite morphology of materials separated from coal. In Proceeding of 10th National Meeting of American Society of Surface Mining and Reclamation, Vol. 2. Spokane, WA, May 16-19,1993. pp. 284-297. 

Utter, T. (1978) Morphology and geochemistry of different pyrite types from the upper Witwatersrand system of the Klerksdorp Goldfield South Africa. Geol. Rundschau, 67(2), 774-804. 

Organic sulfur is the dominant form in peats described in these studies. Pyrite, however, is abundant in brackish and marine peats, occurring in void spaces in or between plant debris (3). In a study of pyrite formation in freshwater peats, Altschuler et al. (5) determined parallel decline in ester sulfate with increases in pyrite as depth increased and concluded that pyrite formed at the expense of organic sulfur. In general, framboidal morphology is present at all salinities. Altschuler et al. (5) and Lowe and Bustin (10) found monosulfides to be minor in peats. 

A record of morphology classes for each pyrite occurrence was kept during petrographic analyses. Monocrystalline pyrite includes euhedral and subhedral pyrite crystals. This morphology class is always more prevalent than framboidal pyrite except at the top of core 1 and the bottom of core 3. 

Beside defects from mineral genesis, grinding of a mineral can produce roentgen amorphous states or a new crystalline phase. This leads to the formation of surfaces which differ morphologically and energetically from equilibrium surfaces. Relations were also observed between the degree of crystallinity and particle size on one side and surface reactivity with water or a surfactant on the other side. For example, the adsorption of xanthates on a very pure surface of pyrite monocrystals occurs much slower than on fine crystalline samples5. ... 

Pyrite oxidation includes biological and electrochemical reactions, and varies with pH p02, specific surface, morphology, presence or absence of bacteria and/or clay miner-... 

Metastable Iron Sulfides Organic Sulfur Elemental Sulfur MECHANISM OF PYRITE FORMATION. 4.1 Evidence from Experimental Studies. 4.2 Isotope Effects during Experimental Pyrite Formation. 4.3 Origin of Morphological Variations in Pyrite SULFUR DIAGENETIC PROCESSES IN MARINE SEDIMENTS. 5.1 Depth Distribution of Diagenetic Sulfur Products. 5.2 Rates of Sulfate Reduction... 

The discussion thus far has assumed a syngenetic origin for the pyrite. Observations of sulfide morphology suggest that at least some of the sulfide may be epigenetic. Edwards and Baker (32) showed that pyrite forms in marine environments whereas marcasite forms under more acidic conditions. Recent experimental work has shown that pyrite forms at a pH of 5.0, whereas marcasite forms at a pH of... 

Small particles, 2p, or veinlets disseminated in the coal. Microscopic pyrite occurs in five basic morphology types ... 

Morphology of Typical Pyrite Species on Deposit Surface... 

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