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ISOLATION OF PYRITE SPHERULES FROM RECENT SEDIMENTS
Author(s) -
Vallentyne J. R.
Publication year - 1963
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1963.8.1.0016
Subject(s) - pyrite , sulfur , sediment , sulfate , sedimentation , mineralogy , geology , organic matter , environmental chemistry , total organic carbon , carbon fibers , mineral , geochemistry , chemistry , geomorphology , materials science , organic chemistry , composite number , composite material
A microscopic examination of approximately 200 sediment samples, mostly freshwater in origin, revealed an abundance of pyrite spherules in virtually all fine‐grained deposits that contained organic matter and reduced sulfur compounds. A speciel study was made of the spherules in deep‐water sediments of Little Round Lake, Ontario. The spherules there numbered approximately 450,000 per gram of dry sediment, accounting for 0.6% of the inorganic matter in the sediment. They ranged in diameter from 2 to 100 µ , but 75% or more had a diameter less than 11 µ . A method is described for the isolation of spherulitic pyrite from recent sediments based on heavy mineral centrifugation, flotation of pyrite spherules, and differential sedimentation of pyrite after rupturing the spherules into their component microcrystals. A sample of spherulitic pyrite isolated from the sediments of Little Round Lake was composed as follows: 53.16% sulfur, 46.59% iron, 0.13% silicon and 0.009% carbon, with only 0.11% of the weight unaccounted for. The silicon was thought to be partly due to contamination from other heavy minerals. Calculations based on the observed carbon content made it seem unlikely that the spherules could contain the organic microfossils that other workers have reported. The sulfur in the pyrite showed a 0.4% depletion in S 34 as compared to sulfate‐sulfur in the surface water of the lake. Attempts to synthesize pyrite spherules in the laboratory were unsuccessful.