scholarly journals The Au-Hosting Minerals and Process of Formation of the Carlin-Type Bojitian Deposit, Southwestern China

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-22 ◽  
Author(s):  
Kai Hu ◽  
Moucheng Pan ◽  
Jian Cao ◽  
Yin Liu ◽  
Shanchu Han
Keyword(s):  
Solid Solution ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Guizhou Province ◽  
Coarse Grained ◽  
Gold Solution ◽  
Medium Temperature ◽  
Southwestern Guizhou ◽  
Southwestern Guizhou Province ◽  
Reducing Environment

The recently discovered middle-sized Bojitian Carlin-type Au deposit is located in southwestern Guizhou Province, China, near the well-known Shuiyindong super-large-sized deposit. To improve the understanding on this deposit, here we investigate the minerals that host Au and the occurrence of Au in the deposit, using a combination of microscopic work and electron probe microanalysis (EPMA). Based on the results, the formation of the deposit was addressed. Results indicate that the dominant minerals that host Au include arsenian pyrite and arsenopyrite. Au in the cores of zoned pyrite exists mainly as natural nanoscale Au (Au0), while Au in the rims exists mainly as solid solution Au (Au+), but it likely also exists in the rims as natural nanoscale Au. The framboidal, coarse-grained, and banded pyrite types contain both natural nanoscale Au0 and solid solution Au+. The arsenopyrite is of hydrothermal origin, and Au within the arsenopyrite exists as gold solution Au+. The Bojitian deposit was formed from As-bearing, H2S-rich, low-to-medium-temperature fluids that migrated along faults and other channels. Au that was already present in the strata or source beds migrated with the fluids in the form of Au(HS)− and ore-forming fluids were then formed in the reducing environment. The ore-forming fluids interacted with Fe-rich carbonates to form an abundance of Au-hosting arsenian sulfides.

Electron microprobe study of turquoise-group solid solutions in the Neyshabour and Meydook mines, northeast and southern Iran

2020 ◽  
Vol 58 (1) ◽  
pp. 71-83
Author(s):  
Elahe Mansouri Gandomani ◽  
Nematollah Rashidnejad-Omran ◽  
Amir Emamjomeh ◽  
Pietro Vignola ◽  
Tahereh Hashemzadeh
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Electron Microprobe ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Major Elements ◽  
Point Of View ◽  
Chemical Compositions ◽  
Light Blue ◽  
Quaternary Solid Solution

ABSTRACT Turquoise, CuAl6(PO4)4(OH)8·4H2O, belongs to the turquoise group, which consists of turquoise, chalcosiderite, aheylite, faustite, planerite, and UM1981-32-PO:FeH. In order to study turquoise-group solid solutions in samples from the Neyshabour and Meydook mines, 17 samples were selected and investigated using electron probe microanalysis. In addition, their major elements were compared in order to evaluate the feasibility of distinguishing the provenance of Persian turquoises. The electron microprobe data show that the studied samples are not constituted of pure turquoise (or any other pure endmember) and belong, from the chemical point of view, to turquoise-group solid solutions. In a turquoise–planerite–chalcosiderite–unknown mineral quaternary solid solution diagram, the chemical compositions of the analyzed samples lie along the turquoise–planerite line with minor involvement of chalcosiderite and the unknown mineral. Among light blue samples with varying hues and saturations from both studied areas, planerite is more abundant among samples from Meydook compared with samples from Neyshabour. Nevertheless, not all the light blue samples are planerite. This study demonstrates that distinguishing the deposit of origin for isochromatic blue and green turquoises, based on electron probe microanalysis method and constitutive major elements, is not possible.

Contribution to the knowledge of the cavernicolous beetle genus Aspidaphaenops Uéno from Guizhou (Coleoptera: Carabidae: Trechinae)

Zootaxa ◽  
2018 ◽  
Vol 4422 (2) ◽  
pp. 244 ◽  
Author(s):  
MINGYI TIAN ◽  
SUNBIN HUANG
Keyword(s):  
New Species ◽  
Southwest China ◽  
Ground Beetle ◽  
Guizhou Province ◽  
New Information ◽  
Southwestern Guizhou ◽  
Two New Species ◽  
Southwestern Guizhou Province ◽  
Male Genital

The hypogean ground beetle genus Aspidaphaenops Uéno, 2006 is reviewed. Some new information of A. reflexus Uéno, 2006 is provided, including the male genital characteristics as well as a new locality. Two new species are described and illustrated from southwestern Guizhou Province, southwest China: A. xiongda n. sp. (Guizhou: Anlong: Fengyan Dong), A. dudou n. sp. (Guizhou: Xingyi: Xiaozi Dong). A key to all Aspidaphaenops species is also provided. 

Experimental Determination of Isothermal Section at 1050°C in the Fe-Nb-V Ternary System

2015 ◽  
Vol 757 ◽  
pp. 1-5
Author(s):  
Chang Jiang Liu ◽  
Qiu Juan Lv ◽  
Zhi Qing Guo ◽  
Yan Jiao Li ◽  
Jian Feng Guo
Keyword(s):  
Solid Solution ◽  
Isothermal Section ◽  
Ternary System ◽  
Phase Equilibria ◽  
Experimental Determination ◽  
Optical Microscopy ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Microalloyed Steels

The phase equilibria in the Fe-Nb-V ternary system were investigated by means of optical microscopy, electron probe microanalysis. One isothermal section in the Fe-Nb-V ternary system at 1050 °C was firstly experimentally established. Present experimental results indicate that: (1) there is a large (Nb, V) continuous bcc solid solution; (2) there are the larger solubilities of V in the FeNb and Fe2Nb phases. The newly determined phase equilibria in this system will provide important support for the development of microalloyed steels.

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