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Petrographic observations of iron, copper, and zinc sulfides in freshwater canal sediment

D. J. Large, N. J. Fortey, A. E. Milodowski, A. G. Christy and J. Dodd
Petrographic observations of iron, copper, and zinc sulfides in freshwater canal sediment
Journal of Sedimentary Research (January 2001) 71 (1): 61-69


Sulfide minerals are known to be important hosts for metals in many freshwater and marine sediments, but little is known about their petrography, particularly in fine-grained recent freshwater sediments. In this paper the results of a Cryogenic SEM investigation of sulfide textures in two fine-grained anaerobic canal-bed muds are reported. The technique allows direct observation of the undisrupted mineral and organic textures in the canal-bed mud. Iron sulfides occur in two forms: coatings on biofilms and framboids. Iron sulfide-coated biofilms have iron sulfur ratios in the range FeS to Fe (sub 3) S (sub 4) . Framboid structures display a continuum of textures from greigite proto-framboids with a poorly developed crystallite texture to pyrite framboids with well developed crystallites. Proto-framboids tend to be smaller than framboids. A positive correlation was observed between crystallite diameter and framboid diameter. By dividing the framboid diameter by the crystallite diameter it was deduced that framboids tend not to have single crystallites at their centers. Copper occurs as a discrete sulfide with a composition similar to chalcopyrite. Zinc occurs as a zinc iron sulfide with metal-to-sulfur ratios in the range 0.59 to 0.87. Copper sulfides tend to nucleate on surfaces whereas the zinc sulfides occur both on surfaces and as floccular precipitates in open pore space.

ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 71
Serial Issue: 1
Title: Petrographic observations of iron, copper, and zinc sulfides in freshwater canal sediment
Affiliation: University of Nottingham, School of Chemical, Environmental and Mining Engineering, Nottingham, United Kingdom
Pages: 61-69
Published: 200101
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 36
Accession Number: 2001-036557
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch map
N52°40'44" - N52°40'44", W01°29'33" - W01°29'33"
Secondary Affiliation: British Geological Survey, GBR, United KingdomAustralian National University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200111
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