Guite, the spinel-structured Co2+Co3+2O4, a new mineral from the Sicomines copper–cobalt mine, Democratic Republic of Congo

作者：Zhilan Lei, Xinghai Chen, Jianxiong Wang, Yingchun Huang, Fangfang Du, Zier Yan · 发表于：Mineralogical Magazine · 年份：2022 · DOI：10.1180/mgm.2022.27 · 被引用次数：10 · 研究领域：X-ray Diffraction in Crystallography、Crystal Structures and Properties、Geological and Geochemical Analysis

Abstract Guite (IMA2017-080), Co 3 O 4 , is a new mineral species and an important economic mineral found in the Sicomines copper-cobalt mine, located ~11 km southwest of Kolwezi City, Democratic Republic of Congo. The mineral occurs as a granular agglomerate, 50 to 500 μm in size, and is associated closely with heterogenite in a quartz matrix. Guite is opaque, has a dark grey colour with metallic lustre and a black streak. In reflected light microscopy, it is white with no internal reflections. The reflectance values (in air, R in %) are: 27.0 (470 nm); 25.6 (546 nm); 25.2 (589 nm), and 24.6 (650 nm). The average of 20 electron-microprobe analyses is Co 71.53, Cu 0.58, Mn 0.67, Si 0.25, O 26.78, total 99.82 wt.%, corresponding to the empirical formula calculated on the basis of 4 O apfu: (Co 2+ 0.92 Cu 2+ 0.02 Si 4+ 0.02 ) Σ0.96 (Co 3+ 1.98 Mn 3+ 0.03 ) Σ2.01 O 4.00 , with Co 2+ and Co 3+ partitioned using charge balance. The ideal formula is Co 2+ Co 3+ 2 O 4 . Guite is cubic with space group Fd $\bar{3}$ m . The unit cell parameters refined from the single crystal X-ray diffraction data are: a = 8.0898(1) Å, V = 529.436(11) Å 3 and Z = 8. The calculated density of guite is 6.003 g/cm 3 . The eight strongest observed powder X-ray diffraction lines [ d in Å ( I/I0 ) ( hkl )] are: 4.6714 (16.7) (111), 2.8620 (18.4) (220), 2.4399 (100) (311), 2.3348 (10.4) (222), 2.0230 (24.8) (400), 1.5556 (26.3) (511, 333), 1.4296 (37.7) (440) and 1.0524 (10.1) (731, 553). The crystal struct...