A THERMODYNAMIC STUDY OF PYRITE AND PYRRHOTITE
A THERMODYNAMIC STUDY OF PYRITE AND PYRRHOTITE
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DOI：
10.1016/0016-7037(64)90083-3
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发表时间：
1964-01-01
影响因子：
5
通讯作者：
BARTON, PB
中科院分区：
文献类型：
--
作者：
TOULMIN, P;BARTON, PB
通过使用电子无光法，发现了磁黄铁矿的组成、硫的逸度和温度之间的相互关系：式中fs2为1atm时硫相对于理想双原子气体的逸度，Nis为磁黄铁矿（在FeS- s2体系中）中FeS的摩尔分数，以及绝对温度。方程的实验不确定度为0-003 inN。磁黄铁矿中FeS （aFeS）在考虑温度下相对于纯物质的活度根据Gibbs-Duhem关系由上式得出；电子光泽法使我们能够测定fs2vs。从743°C到325°C，磁黄铁矿-黄铁矿-蒸汽组合不变的t曲线。我们对磁黄铁矿组成的测定与阿诺德的结果非常吻合。黄铁矿饱和磁黄铁矿中FeS的活性与单体非常不同，这一事实极大地影响了涉及磁黄铁矿的其他一些相平衡研究的解释及其在硫化物矿物组合中的应用，但对热液或岩浆流体组成的更一般计算几乎没有影响。根据可用的体积数据计算出的压力对相的影响很小。
Through the use of the electrum-tarnish method the following equation has been found to interrelate the composition of pyrrhotite, fugacity of sulfur, and temperature: In this equation fs2is the fugacity of sulfur relative to the ideal diatomic gas at 1 atm,Nis the mol fraction of FeS in pyrrhotite (in the system FeS-S2), andTthe absolute temperature. The experimental uncertainty in the equation is 0–003 inN. The activity of FeS (aFeS) in pyrrhotite relative to the pure substance at the temperature of consideration follows from the above equation by virtue of the Gibbs-Duhem relation; it is given by:The electrum-tarnish method has permitted us to determine the fs2vs.Tcurve for the univariant assemblage pyrrhotite-pyrite-vapor from 743 to 325°C. Our determinations of the composition of pyrrhotite are in excellent agreement with the results of Arnold. The activity of FeS in pyrite-saturated pyrrhotite is very different from unity, a fact that greatly influences the interpretation of some other phase equilibrium studies involving pyrrhotite and their application to sulfide mineral assemblages, but has little effect on the more general calculations of composition of hydrothermal or magmatic fluids.Pressure effects calculated from available volumetric data on the phases are small.