三家金矿发现Hg-Au-Ag矿物——α-汞金银矿

Alpha-Goldamalgam, a Hg-Au-Ag Variety of Au-bearing Minerals Found in the Sanjia Gold Deposit, Hebei Province

a-汞金银矿是1986年笔者在河北省青龙县三家金矿某富矿带采集的金矿石标本中发现的,见于矿石光片及人工重砂中。经电子探针分析,平均含Ag 41.53%,Au 22.34%,Hg 36.09%,简化化学式为:(Ag,Au)3Hg。其x射线粉晶数据为:2.382(9) (111),2.060(6)(200),1.461(7)(220),1.245(10)(311),1.194(5)(222),与1929年Pabst等人合成的a汞金矿(含Au 82.75%)可以比较,属等轴晶系。笔者确定它为Hg、Au、Ag金属互化物,且是Hg-Au-Ag系列矿物的新变种。

Samples containing alpha-goldarnalgam were collected from the Sanjia gold deposit, Qinglong County, Hebei Province. Alpha-g01damalgam was found in polished sections, heavy mineral samples and bulk ore samples.Electron microprobe analyses indicate that the mineral is composed of Ag 41.53%, Au 22.34% and Hg 36.09%, its average molecular formula is (Ag_(2.14)Au_(0.63))_(2.77)Hg, and its simplified chemical formula is (Ag, Au)_3Hg. Au, Ag and Hg are uniformly distributed in the mineral.Alpha-goldamalgam occurs as very fine spherio particles or irregular gra, nular aggregates with bright yellowish white color, strong metallic luster and low hardness(Vickers hardness 92.23 kg/mm^2, corresponding to Mohs' hardness 3.05). Under microscope it is homogeneous with rosy bright yellowish white and bright white colors but without double reflection and pleochroism.The reflectance data are as follows: Wavelength (nm) 480 546 591 654 Reflectance (%) 76.22 82.70 86.35 89.05Its X-ray powder analytical data are 2.382(9)(111),2.060(6)(200),11461 (7)(220),1.245(10)(311) and 1.194(5)(222), comparable with the data of alpha-gold-merCury. Its crystal structure is of isometric system with a being 4.129 and space group Fm3m.