Determining compositional trends among individual minerals is key to understanding the thermodynamic conditions under which they formed and altered, and is also essential to maximizing the scientific value of small extraterrestrial samples, including returned samples and meteorites. Here we report the chemical compositions of Fe-sulfides, focusing on the pyrrhotite-group sulfides, which are ubiquitous in chondrites and are sensitive indicators of formation and alteration conditions in the protoplanetary disk and in small Solar System bodies. Our data show that while there are trends with the at.% Fe/S ratio of pyrrhotite with thermal and aqueous alteration in some meteorite groups, there is a universal trend between the Fe/S ratio and degree of oxidation. Relatively reducing conditions led to the formation of troilite during: (1) chondrule formation in the protoplanetary disk (i.e., pristine chondrites) and (2) parent body thermal alteration (i.e., LL4 to LL6, CR1, CM, and CY chondrites). Oxidizing and sulfidizing conditions led to the formation of Fe-depleted pyrrhotite with low Fe/S ratios during: (1) aqueous alteration (i.e., CM and CI chondrites), and (2) thermal alteration (i.e., CK and R chondrites). The presence of troilite in highly aqueously altered carbonaceous chondrites (e.g., CY, CR1, and some CM chondrites) indicates they were heated after aqueous alteration. The presence of troilite, Fe-depleted pyrrhotite, or pyrite in a chondrite can provide an estimate of the oxygen and sulfur fugacities at which it was formed or altered. The data reported here can be used to estimate the oxygen fugacity of formation and potentially the aqueous and/or thermal histories of sulfides in extraterrestrial samples, including those returned by the Hayabusa2 mission and due to be returned by the OSIRIS-REx mission in the near future.

确定单个矿物之间的成分趋势是了解它们形成和改变的热力学条件的关键，也是最大限度地提高小型外星样本（包括返回样本和陨石）的科学价值的关键。在这里，我们报告了 Fe 硫化物的化学成分，重点是磁黄铁矿族硫化物，它们在球粒陨石中无处不在，是原行星盘和小型太阳系天体中形成和改变条件的敏感指标。我们的数据表明，虽然在一些陨石群中，随着热蚀变和水蚀变，磁黄铁矿的 at.% Fe/S 比率存在趋势，但 Fe/S 比率和氧化程度之间存在普遍趋势。在以下过程中，相对还原的条件导致了陨硫铁的形成：(1) 原行星盘中球粒形成（即原始球粒陨石）和（2）母体热改变（即 LL4 到 LL6、CR1、CM 和 CY 球粒陨石）。氧化和硫化条件导致在以下过程中形成具有低 Fe/S 比率的贫铁磁黄铁矿：（1）水蚀变（即，CM 和 CI 球粒陨石），和（2）热蚀变（即，CK 和 R 球粒陨石）。在高度水化蚀变的碳质球粒陨石（例如，CY、CR1 和一些 CM 球粒陨石）中存在硫钛矿表明它们在水相蚀变后被加热。球粒陨石中陨硫铁、贫铁磁黄铁矿或黄铁矿的存在可以估计其形成或改变时的氧和硫逸度。