内蒙古东升庙多金属硫铁矿床中首次发现自然铁

FIRST DISCOVERY OF NATIVE IRON IN DONGSHENGMIAO POLYMETALLIC SULFUR DEPOSIT, INNER MONGOLIA

内蒙古东升庙多金属硫铁矿中首次发现的自然铁赋存于硅质火山熔结角砾岩中。自然铁呈钢灰色至铁黑色。新鲜断口呈亮银白色，强金属光泽。不透明。硬度４．０２。比重７．８６。具延展性和强磁性。反光显微镜下呈亮银白色。主波长（ｕｍ）的反射车（％）──４７０：６４．７９；５４６：７７．０５；５８９：７９．４５；６５０：８２．４９。电子探针分析Ｆｅ含量为９８．２７％。其主要粉晶谱线：２．０２２（１１０），１．４３１（２００），１．１６６（２１１），１．０１２（２２０）。等轴晶系，晶胞参数ａ０＝０．２８６６４ｕｍ。ｚ＝２。空间群：－Ｉｍ３ｍ。据其Ｘ射线粉晶数据和化学成分定名为α－自然铁。它可能形成于硫铁矿化的石英角斑岩或富铁的拉斑橄榄玄武岩，因海底火山喷发作用，氧逸度升高，导致铁橄榄石经歧化反应，形成自然铁和石英。其发现有重大地质意义。

AbstractNative iron is found for the first time with in the volcanic silliceous breccia in Dongshengmiao polymetallic pyrite deposit in Inner Mongolia. The new species of mineral occurs as opaque, light to dark pale and silver white on fresh fracture or under reflected light microscope, with strong metallic luster, ductility, strongly magnetic property, 4. 02 hardness, 7. 86 specific gravity and reflectivities of 64. 79%, 77. 05%, 79. 45% and 82. 49% respectively for wavelengths of 470nm, 546nm, 589nm and 650nm. Microprobe analysis shows an iron content of 98. 2% in the species while X- ray diffraction analysis gives the following crystallogeometric data: main spectral lines of 2. 022 (110), 1. 431 (200), 1. 166 (211 ) and 1. 012 (220), unit cell parameters of a0= 0. 286 64nm and Z= 2, and space group of OZ-Im3m. All this provides for properly naming the new mineral as native iron (α-Fe).