向陽雲母礦床之礦物組成與成因

The Mineral Assemblage and Genesis of Mica Deposits in Hsiang-Yang Region

陳家齊(Cha-Chi Chen) ； 陳惠芬(Huei-Fen Chen) ； 方建能(Jiann-Neng Fang) ； 楊智豪(Chih-Hao Yang)

《臺灣鑛業》 66卷4期 (2014/12) Pp. 1-10

摘要

本文將討論由臺東向陽礦區不同地點所採集的雲母礦樣本之礦物組成、產狀和成因，在礦物組成方面藉由X光粉末繞射鑑定礦物種類和純度，並使用雷射粒徑分析儀分析其粒徑分布。依照野外產狀的觀察和礦物組成的結果可將本區白雲母礦分為三大類，第1類以區域變質作用為主，具有透鏡狀石英脈填充且劈理發達的白雲母片岩，表面經氧化過呈現黃色，顆粒度大且粒徑分布不平均，為本區成分最純的白雲母。第2類也屬於區域變質型，且劈理發達的白雲母片岩，以夾層型態夾在綠泥石片岩中，其白雲母的含量亦純，但含有少量的鈉鉀雲母和鈉長石，礦物顆粒較粗，粒徑分布較不平均。第3類為熱液蝕變或風化作用後形成的細顆粒絹雲母，其礦物成分與礦區開採後運送至選礦廠的樣品成分較為相近，含有綠泥石和少量方解石。石英在所有樣本中幾乎都有出現，經洗選過後的樣本石英含量明顯降低許多。長石多出現在第1和第2類區域變質作用類型。在第3類的熱液蝕變絹雲母中，長石含量幾乎消失，可能形成次生的葉蠟石。向陽公司目前開採的絹雲母樣本成分和第3類組成類似，以細顆粒的絹雲母為主，然洗選後的樣本仍含有少量的綠泥石和葉蠟石組成。

關鍵字

絹雲母 ； 白雲母 ； X光粉末繞射 ； 粒徑分析 ； 熱液蝕變

並列摘要

In this study, we examined and discussed the components, occurrences and genesis of mica samples, which were collected at different locations in Hsiang-Yang region, Taitung. The components and purity of mineral are identified by X-ray powder diffraction (XRD) and particle size distribution was determined by a Laser Particle Size Analyzer. According to the field observation and mineral assemblages the genesis of muscovite can be divided into three types. The first type belongs to the muscovite schist formed by regional metamorphism, it is marked with quartz veins and well-developed cleavage. The sample of this type has the purest muscovite, which shows a yellowish surface because of oxidation. The particles are coarse in non-uniform size distribution. The second type is also muscovite schist, which has well-developed cleavage, appeared interlayerly between chlorite schist by regional metamorphism. The mineral content of this type bears pure muscovite without other clay minerals, and bears a little wonesite and plagioclase. The grain sizes are coarse and broadly distributed. The third type is fine-sized sericite which was formed by hydrothermal alteration or weathering. The mineral components of this type are similar to the final water classified products from the mining area. Besides sercite, both of them also contain chlorite and a little calcite. Quartz almost appears in all three types, but its content decreases evidently after washing. Plagioclase only appears in the first and second types derived from regional metamorphism origin. The third type sericite, which lacks plagioclase, was derived from hydrothermal alteration. In the hydrothermal alteration process, plagioclase has altered to form secondary pyrophyllite. The component of excavated sericite sample by Sunshine Mining Company is similar to the third type in this study, because it is finer particles also bears some chlorite and pyrophyllite after washing.

並列關鍵字

Sericite ； Muscovite ； X-Ray Diffraction ； Laser Particle Size Analyzer ； Hydrothermal alteration