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Mineral assemblages in sulfide ores; the system Cu-Fe-S-O

Hugh Exton McKinstry
Mineral assemblages in sulfide ores; the system Cu-Fe-S-O
Economic Geology and the Bulletin of the Society of Economic Geologists (September 1959) 54 (6): 975-1001

Abstract

The paper presents the evidence supporting ternary phase diagrams proposed in earlier articles and builds a quaternary diagram making use of observed mineral associations to supplement available chemical data. Phase relations explain the rarity or absence of a number of associations such as magnetite-covellite, pyrrhotite-hematite and, in the presence of magnetite, bornite-pyrite. Although most commonly observed assemblages are apparently stable over a wide range of temperatures there is a strong suggestion of shifting of tie-lines with change of temperature within the field of composition bounded by chalcocite, covellite, chalco-pyrite, and pyrite. The observed sequence in ore deposition is not so much a sequence of individual minerals as a sequence of assemblages, each higher than the preceding one in ratio of S to O and usually of Cu to Fe. However, it seldom reaches the ultimate high-S assemblage, covellite-pyrite. Late stage reversals of the trend (e.g., chalcocite replacing covellite) could be occasioned by waning of S supply before cooling was far advanced. Certain minerals such as pyrrhotite and magnetite are early members of the sequence, not because they are in themselves "high temperature" minerals, but because they are stable in low-S high-Fe assemblages.


ISSN: 0361-0128
EISSN: 1554-0774
Coden: ECGLAL
Serial Title: Economic Geology and the Bulletin of the Society of Economic Geologists
Serial Volume: 54
Serial Issue: 6
Title: Mineral assemblages in sulfide ores; the system Cu-Fe-S-O
Pages: 975-1001
Published: 195909
Text Language: English
Publisher: Economic Geology Publishing Company, Lancaster, PA, United States
Accession Number: 1959-019877
Categories: Economic geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Update Code: 1959
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