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在西非的象牙海岸Issia地区分布着许多铌钽矿床,包括原生矿和砂矿。原生矿产在分带很好的伟晶岩中。这个地区发育着许多花岗岩和花岗伟晶岩。伟晶岩可分为:(1)分异不好的伟晶岩,无矿化;(2)含Be伟晶岩,分带较好,见绿柱石;(3)含Be-Nb-Ta的伟晶岩,分带很好,是矿体;(4)Be-Nb-Ta-Li伟晶岩,分带很好,是矿体。除了10多个原生矿外,还有许多砂矿。砂矿有两种类型:一种近原生矿的坡积砂矿,另一种是经河流冲刷搬运后的冲积砂矿。我们选择了Etienne-Meguhe砂矿作为近原生矿的坡积砂矿的代表,Bemadi矿作为河流冲积型的砂矿的代表,对这两种类型的砂矿的风化、搬运、沉积机理进行了比较研究。研究发现不同的搬运距离和搬运模式对铌钽砂矿的主要矿物——铌钽铁矿的化学性质没有什么影响,而其物理形态则发生了变化。坡积型砂矿的铌钽铁矿常与石英、长石等矿物连生,其颗粒大小与原生的Nb-Ta伟晶岩中的铌钽铁矿一致;经河流冲积而形成的砂矿中,铌钽铁矿颗粒变小、轮廓变得圆滑,几乎无连生矿物,但矿体集中,常在河流的冲积扇中分布,易开采。
There are many Nb-Ta deposits in Issia, Ivory Coast of West Africa, including primary and secondary ores. Primary minerals are well-pegged pegmatites. There are many granite and granitic pegmatites in this area. Pegmatite can be divided into: (1) non-well-differentiated pegmatite, non-mineralized; (2) Be pegmatite, zoning is better, see beryl; Of pegmatite, zoning is very good, is the ore body; (4) Be-Nb-Ta-Li pegmatite, zoning is very good, is the ore body. In addition to more than 10 primary mines, there are many placer mines. There are two types of placer ore: one is a slope sedimentary ore near the primary ore and the other is an alluvial sand mine that is washed and transported by the river. We have chosen the Etienne-Meguhe sandstone as a representative of the Slope Alluvial Deposit near-primary ore, and the Bemadi ore as a representative of fluvial alluvial sandstone, comparing the weathering, handling and sedimentation mechanisms of these two types of sand the study. The study found that different transport distances and handling patterns had no effect on the chemical properties of niobate tantalite, the major mineral in the tantalum-tantalum ore, while its physical morphology changed. The tacrolimite columbite is often associated with quartz, feldspar and other minerals, and its grain size is consistent with the niobium tantalite in the native Nb-Ta pegmatite. Among the plagioclase formed by river alluvial deposits, Niobium tantalite particles become smaller, the outline becomes sleek, almost no ancillary minerals, but the ore body is concentrated, often in alluvial fans of the river distribution, easy mining.