Micro-Raman Spectral Characteristics and Implication of FeS2 from Metamorphic Belt between Coal and Intrusion in Wolonghu Coal Mine of Anhui Province, China

Some FeS2 samples among metamorphic belt between coal and intrusion from Wolonghu mine in the north of Anhui Province were retrieved to characterize the signature of Raman Spectral. The results show that, all Raman data of different samples can be divided into 3 types as I, II and III according to distinct differences of in Raman mode (M), Raman shift (Delta nu) and scattering intensity (I). There are five strong scattering modes including high value E-g (1.16 similar to 1.59 X 10(3)), high value A(g) (2.33 similar to 2.53 X 10(3)) and low value T-g (0.20 similar to 0.27 X 10(3)) in type I and only former three modes in type II although the value of E-g, A(g) and T-g are similar between them. While there are only two modes of high value E-g about 327.6 similar to 328.8 cm(-1) and low value A(g) 389.0 similar to 390.1 cm(-1). Our analyses indicate that type I samples must be mixed crystal of pyrite and natural coke for the former three peaks are same to deformation and stretching vibration of Fe-[S-2](2-) and stretching vibration of S-S in pyrite, while the latter two are similar to the vibration of Tiny graphite crystals and stretching vibration of C-C among graphite crystal from Raman data. And type II sample may be pyrite for typical pyrite Scattering peak and Type III sample possibility are low-temperature crystalloblastic of pyrite for Marcasite spectrum features in Raman. Further analysis also showed that the formation pressure of type I and II are the same while type 111 samples formed in low pressure for Raman scattered intensity of type I and II are similar, and type III samples is obviously lower than the former two. And the formation temperature of type I, type II and type 111 significantly decreased in turn for A(g) peak of them are turn to high frequency about 4.4 similar to 6.7, 4.5 similar to 8.4cm(-1) respectively compared with the former. Thus, The authors' studies suggest that pyrite samples from Metamorphic coal and metamorphic zone in Wolonghu coal mine are products in high temperature, but samples from Magmatic rocks are Marcasite formed at low temperature.