- 期刊
臺灣高鋁礦産之調查研究：大屯山低品位鋁礬土礦之形成及其礦物特性
Investigations of High Aluminum-Bearing Minerals in Taiwan: Mineralogy and Formation of the Tatun Low Grade Bauxite Deposit
摘要
礦業研究所在大屯火山羣周緣臺地及丘陵地所發現低品位鋁礬土礦，經廣泛採樣，並以X光繞射、X光螢光分析、加熱減量及高溫礦物變化試驗、掃瞄式電子顯微鏡及電子微探分析，研究結果顯示：多孔性三水鋁礦（gibbsite）爲風化安山岩質火山灰中之主要含鋁礦物。樣品中雜質爲細粒石英，針鐵礦，磁鐵礦及少量包括鋁英石在內之粘土礦物。氧化鋁含量爲25-45%，二氧化矽15-45%，三氧化二鐵10-15%及二氧化鈦1.1-1.4%。鹼性和鹼土族金屬及部分矽元素均受化學風化作用溶濾而去。粒度分析顯示50%平均粒經爲0.3mm。大屯鋁礬土之母岩爲安山岩質火山灰。本區雨量豐富，年雨量達3,000至5,000公厘，屬亞熱帶氣候，低地地勢平緩，火山灰PH值5-6，質疏鬆，雨水可自由流動，爲構成鋁礬土之理想條件。
關鍵字
無資料並列摘要
Several hundreds of samples collected from Tatun Volcano group were analyzed by X-ray diffraction and X-ray fluorescence methods. Part of them were studied by thermogravimetric and electron microprobe analysis and scanning electron microscopy. The results showed that the massive and loosely cohered materials were composed mainly of gibbsite, fine grain quartz, goethite, magnetite and a small amounts of clay minerals including allophanes. Chemical composition falls within the limit of 25 to 45% Al_2O_3, 15 to 45% SiO_2, 10 to 15% Fe_2O_3 and 1.1 to 1.4% TiO_2. Most of the alkali and alkaline earth metals with part of Si were leached away by chemical weathering. Particle size analyses show that mead value of 50 cumulative weight percentage is 0.3mm. The favored conditions for this bauxite formation are believed to be: (1) warm tropical climate, (2) abundant rain fall of 3,000 to 5,000 cm/year, (3) aluminous andesitic volcanic ashes having high permeability and good sub-surface drainage and (4) long periods of tectonic stability that permit deep weathering and preservation of land surfaces.