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Phase Relations in the Cu-Fe-S, Cu-Ni-S, and Fe-Ni-S Systems*

By
G. Kullerud
G. Kullerud
Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C. 20008, Brown University, Providence, R. I. 02912, Heidelberg University, Heidelberg, Germany
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R. A. Yund
R. A. Yund
Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C. 20008, Brown University, Providence, R. I. 02912, Heidelberg University, Heidelberg, Germany
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G. H. Moh
G. H. Moh
Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C. 20008, Brown University, Providence, R. I. 02912, Heidelberg University, Heidelberg, Germany
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Published:
January 01, 1969

Abstract

The phase relations in the Cu-Fe-S, Fe-Ni-S, and Cu-Ni-S systems were investigated by silica-tube quenching, differential thermal analysis, and high-temperature X-ray powder diffraction experiments. In addition, portions of the Cu-Fe-S and Fe-Ni-S systems were studied by gold-tube quenching and differential thermal analysis experiments under high confining pressures.

At elevated temperatures extensive liquid immiscibility fields span the sulfur-rich region of each of the three systems, whereas homogeneous liquid fields dominate the phase relations in their central portions. The average composition of the Sudbury Cu-Fe-Ni sulfide ore, when projected onto the Cu-Fe-S plane, is accounted for above 860° C by a mixture of copper containing hexagonal pyrrhotite and copper-rich sulfide liquid. Thus at high temperatures a mechanism exists that may be responsible for certain copper-rich segregations observed in this type of ore. The minerals of the Cu-Ni-S system, with the rare exception of millerite, do not occur in Sudbury-type ores. Knowledge of the phase relations in this system is prerequisite, however, for systematic investigations of the complex Cu-Fe-Ni-S system. Applications of the phase relations in the Cu-Fe-S and Fe-Ni-S systems to typical ore assemblages show that extensive reequilibration took place among the sulfides after their initial deposition. The sulfides in Sudbury-type ores commonly have compositions and crystal structures that can be produced in the laboratory only at low temperatures.

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Contents

Society of Exploration Geophysicists Geophysical Monograph Series

Magmatic Ore Deposits

H. D. B. Wilson
H. D. B. Wilson
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Society of Economic Geologists
Volume
4
ISBN electronic:
9781934969991
Publication date:
January 01, 1969

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