电子探针和微区X射线衍射研究陕西镇安钨-铍多金属矿床中祖母绿级绿柱石

代鸿章; 王登红; 刘丽君; 黄凡; 王成辉

doi:10.15898/j.cnki.11-2131/td.201712140193

电子探针和微区X射线衍射研究陕西镇安钨-铍多金属矿床中祖母绿级绿柱石

Study on Emerald-level Beryl from the Zhen'an W-Be Polymetallic Deposit in Shaanxi Province by Electron Probe Microanalyzer and Micro X-ray Diffractometer

摘要

摘要: 南秦岭镇安地区发现了以白钨矿-绿柱石为矿石矿物组合的矿床新类型。为查明该矿床中首次发现的翠绿色祖母绿级绿柱石的致色机理并进一步揭示其成矿机制，本文在野外地质调查的基础上，对绿柱石开展了电子探针与微区X射线衍射等矿物学研究。结果表明：矿区中首次发现的祖母绿级绿柱石，呈自形晶产于石英（方解石）脉中并与白钨矿共（伴）生。祖母绿级绿柱石从核部至边缘V₂O₃含量较高，分别为0.64%~0.98%和1.04%~1.42%，且有增高趋势。X射线衍射数据表明区内祖母绿为“正常”绿柱石，同时存在Al↔Me²⁺和Be↔Li两种类质同象替换机制。V为本区祖母绿主要致色元素，来自于区内碳质板岩、金云母片岩及白云质大理岩等地层，Be、Si、Al等主要元素则来自于深部酸性岩浆岩。本次发现为该矿床中钨、铍矿产资源的综合开发利用提供了基础地质资料，并为南秦岭在区域及深部继续寻找稀有金属矿指出新的找矿方向。

Abstract:
BACKGROUND A new deposit type with a scheelite-beryl-molybdenite assemblage was first discovered in the Zhen'an area of Shaanxi Province.
BAOBJECTIVES The research on chromatic mechanism and genetic mechanism of emerald was carried out.
METHODS Combined with the geological survey, Electron Microprobe and in-situ Micro X-ray Diffractomer were used to conduct mineral research.
RESULTS The emerald mainly occurs in the quartz (calcite) veins as euhedral crystal and is associated with scheelite. Both the core and rim of the emerald with high V₂O₃ contents of 0.64%-0.98% and 1.04%-1.42%, respectively, show an increased V₂O₃ trend from core to rim. Diffraction data show that the emerald is normal beryl and has two kinds of isomorphous substitution mechanism, Al↔Me²⁺ and Be↔Li. Vanadium is the main coloring element of emerald and was mainly derived from carbonaceous slate, mica schist, and dolomitic marble, whereas Be, Si and Al were derived from deep acidic igneous rocks.
CONCLUSIONS The discovery provides basic geological data for the comprehensive development and utilization of tungsten and antimony mineral resources in the deposit, and indicates new prospecting directions for continued searching for rare metal deposits in the region and deep areas of the South Qinling.

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