摘要
通过对中国广西卡林型金矿的含金毒砂、黄铁矿及用热液实验方法合成的含金黄铁矿、白铁矿的分析和研究,特别是光电子能谱分析,发现其中存在电子结合能低于自然金(Au^0)的“不可见金”。因而提出金在上述硫化物矿物中由于取代部分硫并与硫呈共价键结合而显负价态的论点。本文亦从金的化学及地球化学性质,毒砂、黄铁矿及白铁矿的晶体化学特征和产出的地球化学环境等三方面初步探讨了其形成的可能性。
In recent years 'invisible gold' occurring in sulfide minerals of the Carlin disseminated type gold deposits has attracted wide attention. At present, the most important progress on the study of 'invisible gold' comes from the study of Moss-bauer spectra. F.E. Wagner et al. (1986-1992) confirmed that in gold-bearing py-rite and arsenopyrite there exist 'chemical bound gold' that is different from not only native gold (Au?but also other known gold compounds. The chemical valence state of such 'chemical bound gold' in arsenopyrite and pyrite, however, remains unclear.The 'invisible gold'-bearing arsenopyrite and pyrite occurring in the Carlin -type gold deposits of Guangxi, China, and hydrothermally synthesized gold-bearing pyrite and marcasite are investigated in detail, particularly by X-ray photoelectron spectrum (XPS) analysis. The binding energy was adjusted to give the values of 82.5eV-83.5eV for the Au 4f7/2 peak of these minerals. They were obviously lower than Au 4f7/284.0eV of metal gold (Au0). The data of the binding energies of gold -bearing sulfides measured are notably lower than those of Au0, Au1+ and Au3+ in other gold compounds, indicating that the gold in these sulfides is neither zero-valent nor positive valence (nor loses its valence electron), but gains or shares such a valence electron or electrons in combining with an other element. Therefore we suggest that there is gold occurring in angative charge state in the lattice of these sulfides, as it replaces some sulfur and is combined with sulfur by the cova-lent bond. This paper also preliminarily discusses the possibility and the formation mechanism from the chemistry and geochemistry of gold, the crystal chemistry of arsenopyrite, pyrite and marcasite, the geochemical environment and in combination with the synthetic experimental conditions.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1995年第1期67-77,T001,共12页
Acta Geologica Sinica
基金
国家自然科学基金(4880158)和人事部非教育系统留学回国人员科技活动A类项目共同资助
关键词
卡林型金矿
硫化物
负价态金
金矿床
矿化
Carlin-type gold deposit, sulfide, 'invisible gold', chemical bound gold, negative charge state of gold
