CHENG Jia-long1, CUI Zi-liang1,2*, XIAO Chang-xian3, LU Jia-xu3

(1. Yunnan Institute of Geology & Mineral Resources Exploration, Kunming 650051, China;

2. Yunnan Geology and Mineral Group Co. Ltd., Kunming 650051, China;

3. Tengchong Jinshan Geology and Mineral Technology Service Co., Ltd., Tengchong 679100, China)

Abstract: The Xiangbilin Sn deposit is located in the Longchuanjiang magmatic arc within the Tengchong magmatic arc belt in the Gangdise arc-basn system. The discovered Sn orebodies occurred in stratified and vein-like forms in faults and fracture zones on both sides of the F2, with main ore of the cassiterite-greisen type. The microscopic observation and scanning electron microscopy analysis show that the main ore minerals include cassiterite, wolframite, columbite, pyrite, chalcopyrite, and monazite. Columbite occurred in the form of irregular fine grains, with sizes of 0.02－0.1 mm and semri-euhedral to anhedral granular texture. Electron probe microanalyses show that its main compositional mass fractions include 5.82%－43.74% of Nb, 16.37%－67.71% of Ta, 10.92%－30.43% of O, 1.41%－2.45% of Fe, 7.88%－14.87% of Mn, and 0.16%－2.16% of Sc. Columbite is enriched in the tin secondary concentrate. The study on the occurrence state of columbite and its enrichment in the tin secondary concentrate in the Xiangbiling tin deposit has provided new information for understanding genesis of the Xiangbiling tin deposit, and is of guiding significance for prospecting rare metals such as niobium and tantalum in the study area.

Keywords: Xiangbiling Sn deposit; columbite; scanning electron microscopy analysis; resource perspective

ACTA MINERALOGICA SINICA Vol. 43, No. 4, 2023, Page 565