河北綦村铁矿区氟硅硫磷灰石的发现及初步研究

The Discovery and Study of F-wilkeite in Jicun Iron Mine, Hebei China

本文报道了在国内首次发现的产在河北綦村夕卡岩型铁矿中的氟硅硫磷灰石,它具有六方柱状带双锥面的晶形,呈浅紫色,根据探针成分计算的晶体化学式为(Ca_(9.39),Mg_(0.01),Mn_(0.01),Fe_(0.01),Na_(0.12))_(9.54)[(P_(2.169),Si_(1.936),S_(1.746)_(5.851)O_(24)](F_(1.73),Cl_(0.17)_(1.9)。属于磷灰石—硅磷灰石类质同象系列的中间成员。红外光谱呈现49个吸收频带,其中1148,1040和935cm^(-1)3个醒目的强吸收带分别归属于[SO_4],[PO_4)和[SiO_4)的ν_3振动。DTA曲线显示727℃及1200℃的两个吸热谷;X-射线粉晶衍射数据与美国及日本的硅硫磷灰石基本一致,按六方晶胞指标化a=9.4880,c=6.9082A,v=588.5719A^3,z=1,它形成于500℃以上的温度,经后期的热液蚀变转变成磷灰石、碳磷灰石、滑石和硅灰石膏,它们的微粒集合体交代了氟硅硫磷灰石的表层甚至全部。

F-wilkeite, a rare mineral of silicate sulfite apatite, was discovered for the first time in Jicun mine, Hebei Provine of China in 1986.It occurs as euhedral crystal in calcite and vesuvianite within monticellite skarn and takes the form of hexagonal prism, mersuring 0.5 × 0.5 × 3mm3, with pink colour, No = 1.648, Ne = 1.644, specific gravity 3.04, hardness Hv = 279kg/mm2 (Hm=4.6).The chemical composition of CaO 53.34, MgO 0.03, MnO 0.04, FeO 0.03, Na2O 0.41, SiO2 11.80, P2O5 15.60, SO3 14.16, F 3.34, Cl 0.64, and a small amount of CO2 and H2O, gives a formula of (Ca9.399 Mg0.01, Mn0.01, Fe0.01, Na0.12)9.54 [(P2.169, Si1.9369 S1.74(?))5.251 O24] (F1.73, Cl0.17)1.9. It belongs to the intermediate member between the solid solution series of apatite and ellestadite as end-members.Crystallographic parameters are hexagonal, P63/m, a = 9.4880, c = 6.9082A, V = 538.5719A3 and Z = 1.There are 49 absorption bands in the infrared spectra. The appearing bands at 1148cm-1, 1040cm-1 and 935cm-1 can be assigned to v3 vibration of [SO4], [PO4] and [SiO4] groups respectively. DTA curve shows two endothermic peaks near 727℃ and 1200℃.The products of hydrothermal alteration of wilkeite are apatite, dahllite, talc and thaumasite, and got together as a shell on the surface of wilkeite.