臺灣東部東河地區臺灣藍寶礦床產狀特徵及地球化學特性

本篇主要探討位於臺東東河鄉之寶豐祥寶石採礦場的臺灣藍寶產狀與礦物組成特徵並試探究可能的成因。研究取樣自礦場2014～2019年間產出的臺灣藍寶原石，以顯微拉曼光譜儀配合掃描式電子顯微鏡既X光能量色散能譜儀、雷射剝蝕－感應耦合電漿質譜分析與X光粉末繞射分析之結果，進行元素及微區礦物種類的測定。根據對礦脈產狀、礦物種類及其發育順序之研究結果推論，形成台灣藍寶礦脈之熱液可能經由侵入性火成活動的加熱與反覆的斷層活動影響下，經由斷層破裂面自海岸山脈深處向上擴散，並在淺部岩體的裂隙中沉澱出礦脈。礦脈的銅元素來源，可能由深部斑岩銅礦床或熱液活動初期所生成之“富銅＂錳礦脈供應。由於過去曾報導臺灣藍寶含鈾，具微量放射性，本研究以蓋格計數器偵測礦場採掘坑道現址及玉髓樣本的放射線強度，並經由X光能量色散能譜分析及雷射剝蝕－感應耦合電漿質譜分析的微區定量結果得知，鈾元素以微量元素之態存於臺灣藍寶的矽孔雀石內含物中，但分布並不均勻，其富集特性有別於多數已知的鈾礦床地質背景，值得進一步研究。

關鍵字

藍玉髓；臺灣藍寶；矽孔雀石；都蘭山；寶豐祥礦場；鈾

並列摘要

This research investigates the chrysocolla chalcedony occurrences and mineral composition evolution from the Baofengxiang Mine near Donghe Township, Taitung County in Eastern Taiwan. All of the specimens were collected from several batches of rough products in this quarry from 2014 until 2019. We analyzed mineral composition and micro minerals identification by Micro Raman Spectroscope (MRS), Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy (SEM-EDS), X-ray Diffractometer (XRD) and Laser-Ablation Inductively-Coupled-Plasma Mass- Spectrometry (LA-ICP-MS). The inferred results were based on the occurrence, mineral assemblage and its evolution. The hydrothermal fluid of the chrysocolla chalcedony is heated by volcanic intrusive events and renewed faulting activities. The hydrothermal fluid is lifted up in the fractures to deposit minerals in the upper zone of andesitic host rock. The source of copper iron could be derived from the deeper porphyry copper deposit or Cu-rich manganese deposits that have been caused by the initial stage of hydrothermal activities. Moreover, previous researches mentioned that chrysocolla chalcedony contains uranium and there is very weak radiation in these chrysocolla chalcedony. Therefore, we detected the radiation source by the Geiger-Müller counter in the pit and all types of specimens. Also, we used the SEM-EDS and LA-ICPMS to measure the uranium concentration focused inside the chrysocolla, but it is non-uniform distribution. This occurrence should be a rare case, unlike most known researches about the uranium deposit. This topic deserves more investigation in the future.

並列關鍵字

Chalcedony ； Gem Silica ； Chrysocolla ； Dulan Mountain Range ； Baofengxiang mine ； Uranium

參考文獻

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臺灣東部東河地區臺灣藍寶礦床產狀特徵及地球化學特性

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