The Crystal Structure of Lisiguangite

The crystal structure of lisiguangite, CuPtBiS3, from Yanshan mountains, Chengde Prefecture, Hebei Province, China has been determined by single crystal X-ray diffraction. It belongs to orthorhombic space group P212121 with a = 7.7372（15）A, b = 12.844（3） A, c -- 4.9062（10） A, V = 487.57（17） A^3, Z = 4. The final full-matric least-square refinement on F2 converged with R1 = 0.0495 and wR2 = 0.0992 for 704 observed reflections [I≥2σ（I）]. Lisiguangite is the isomorph of known CuNiSbS3 and CuNiBiS3. Pt^2＋ and Bi^3＋ have the distorted octahedral coordination enviroments composed of two metal and four S and Cu^＋2 has a distorted tetrahedrai coordination environment with four S atoms. Each S atom is surrounded by four metals to give a tetrahedral environment. The crystal structure is a complex 3 dimensional network.

Study on the Crystal of Daomanite

It was not possible to carry out a complete analyses of crystal, as the experiment by Ding and Shi et al.. It＇s analysis precision R=0.25 or more big than this, which value are not satisfied for single crystal study, but we through many test and found the best： [R（int）=14.5%]. The final fullmatix least-squares refinement on F2 converged to R1=0.0791 and wR2=0.1864 for 704 observed reflections [I 3 2s（I）]. Daomanite is orthorhombic system, space group Cmc21, a=3.7520（8））A, b=15.844（4） A, c=5.8516（12） A, α=β=γ=90°. V=347.86（14）A3, Z=4. Daomanite chemical formula is Cu Pt AsS 2. Idealized composition Me＋M2＋M2＋S2=CuS ·PtA s S. There is no other similar mineral in the world.

Jichengite 3CuIr_2S_4·(Ni,Fe)_9S_8,a New Mineral,and Its Crystal Structure

A new mineral,jichengite ideally 3CuIr_2S_4·(Ni,Fe)_9S_8,was found as a constituent of placer concentrates at a branch of the Luanhe River,about 220 km NNE of Beijing.Its associated minerals are chromite,magnetite,ilmenite,zircon,native gold,iridium,ferrian platinum and osmium.The placer is distributed at places around ultrabasic rock,which hosts chromite orebodies,from which PGM originated.Jichengite occurs commonly as massive or granular aggregates.No perfect morphology of jichengite was observed.It is steel gray and opaque with metallic luster and black streak.It has a Mohs hardness of 5,VHN(d) urn 21.65,H_m 4.465,Hv = 268.1 N/um^2.It is brittle and weakly magnetic. Cleavage {010} is rarely observed.No fracture was observed.Density could not be measured because of its too small grain size.Density(calc.) is 7.003 g/cm^3.Reflect light is reddish-brown,without internal reflections.Anisotropism is distinct with grayish or yellowish white in crossed nicols and bluish violetcopper red in uncrossed nicols.Jichengite shows weak pleochroism and strong bireflectance.The reflectance values in air at the Standard Commission on Ore Mineralogy wavelengths are:38.9,34.3 at 470 nm,38.9,34.5 at 546 nm,39.1,35.3 at 590 nm,39.2,36.8 at 650 nm,parallel-axial extinction.The six strongest lines in the X-ray powder-diffraction pattern[d in A,(I),(hkl)]are:3.00(100)(116),2.80(50) (205),2.48.(50)(208),1.916(40)(2,1,10),1.765(60)(220),1.753(50)(2,0,16).Five chemical analyses carried out,yielding the following results:S 25.76(25.49-5.97),Fe 10.03(9.78-10.31),Co 0.78 (0.75-0.81),Ni 12.48(12.32-12.85),Cu 4.77(4.69-4.83),Ir 46.98(46.14-47.89),sum 100.80wt%,which produced a formula(Cu_(1.556)Fe_(0.976))_(2.532)(Ir_(5.063)S_(10.126))·(Fe_(2.7451)Ni_(4.404)Co_(0.273))_(7.422)S_(6.517).The ideal formula is X_(10)Ir_5S_(17.5),which was calculated by single crystal structure analyses,where X=Cu(Ⅱ)+Fe(Ⅱ)+Ni(Ⅱ) +Co(Ⅱ).The single crystal data were collected using a diffractometer with Mo Kαradiation and a graphite monochromate.The crystal system is trigonal with space group R3m and unit cell parameters a=7.0745(14) A,c=34.267(10) A(The superstructure not found),and the final R Indices[with 564 observed reflections,I>2sigma(Ⅰ)]are R_1=0.0495,wR_2=0.1349.The specimens are deposited in the Geological Museum of China.