Typomorphic features and exploration significance of pyrite from the Jincheng gold deposit in Luoshan,Henan Province

Pyrite is the major gold-bearing mineral in the Jincheng gold deposit. According to the comprehensive identification under microscope,the formation characteristics and mineralogical characteristics,the pyrite from the No.Ⅱ ore body can be divided into three generations.Gold mainly occurs in the first and second generation of pyrite.Chemical composition,thermal nature and mode of occurrence of gold in pyrite from the No.Ⅱ ore body show that pyrite was derived from magmatic hydrothermal source.Sulfur isotopes of pyrite have a narrow variation range(2.75‰～5.5‰)with an average of 4.195‰,suggesting that sulfur came mainly from the magmatic source.Thermal test of pyrite shows that thermal coefficient(α) has a large variation(-281.0～466.0 μV/℃) with an average of-148.9～268.2 μV/℃,and thermal conductivity type has mixed characteristics of N-type,P-N type,N-P type and P-type.The thermal characteristics of pyrite of the same generation has a positive vertical zoning trend in space,indicating that the composition of pyrite in this ore deposit is complex,suggesting the features of the superposition of multi-stage hydrothermal solutions.Thermal characteristics of pyrite show clearly two peaks in the histogram,indicating that there are at least two gold mineralization stages.The study of the erosion depth of the ore bodies in central location suggests that there still exists good prospect for concealed gold ore bodies.Typomorphic features of the pyrite can provide an important indication for further expanding gold reserves and search for ore deposits of the same type.