In the present paper the mode of occurence of niobium and tantalum in cassiterite has been studied, suggesting that the two elements are present in the form of individual minerals, namely tapiolite (a new mineral), an...In the present paper the mode of occurence of niobium and tantalum in cassiterite has been studied, suggesting that the two elements are present in the form of individual minerals, namely tapiolite (a new mineral), and brown-red coarse and orange-yellow fine grained alvaralites. The ground sample grains sieved to about 200 mesh are treated with hydrofluoric acid and hydrochloric acid (5:1) to remove alvarolites, followed by the removal of SnO2 with ammonium iodide at 450 ±25℃. The resultant can be taken for the qualitative and quantitative determination of tapiolite. The cassiterite grains ground in the diameter of 1--3mm are repeatedly treated with ammonium iodide to eliminate SnO2, consequently the brown-red alvarolite grains about 1 mm in diameter being visible. After elutriating, the brown-red alvarolite grains are separated from the suspension by means of decantation, followed by the dissolusion of impurities with 10% HOl to obtain the fine-grained alvaralite.The contents of coarse and fine grained alvarolites in cassiterite can be achieved by calculation. Additionally, the quantitative determination has been also carried out on cassiterite sample for the total content of SnO2, quartz, zircon and Nb-, Ta-minerals.展开更多
No report has so far been made in China on geochemistry of zirconium in marine sediments. In the past few years, we have determined zirconium and total rare-earth elements (REE) on 47 samples of sediments from the Eas...No report has so far been made in China on geochemistry of zirconium in marine sediments. In the past few years, we have determined zirconium and total rare-earth elements (REE) on 47 samples of sediments from the East China Sea by extraction-spectrophotometry using BPHA-trichloromethane and arsenazo Ⅲ, PMBP-benzene and arsenazo Ⅲ, respectively. The results are summarized as follows:展开更多
文摘In the present paper the mode of occurence of niobium and tantalum in cassiterite has been studied, suggesting that the two elements are present in the form of individual minerals, namely tapiolite (a new mineral), and brown-red coarse and orange-yellow fine grained alvaralites. The ground sample grains sieved to about 200 mesh are treated with hydrofluoric acid and hydrochloric acid (5:1) to remove alvarolites, followed by the removal of SnO2 with ammonium iodide at 450 ±25℃. The resultant can be taken for the qualitative and quantitative determination of tapiolite. The cassiterite grains ground in the diameter of 1--3mm are repeatedly treated with ammonium iodide to eliminate SnO2, consequently the brown-red alvarolite grains about 1 mm in diameter being visible. After elutriating, the brown-red alvarolite grains are separated from the suspension by means of decantation, followed by the dissolusion of impurities with 10% HOl to obtain the fine-grained alvaralite.The contents of coarse and fine grained alvarolites in cassiterite can be achieved by calculation. Additionally, the quantitative determination has been also carried out on cassiterite sample for the total content of SnO2, quartz, zircon and Nb-, Ta-minerals.
文摘No report has so far been made in China on geochemistry of zirconium in marine sediments. In the past few years, we have determined zirconium and total rare-earth elements (REE) on 47 samples of sediments from the East China Sea by extraction-spectrophotometry using BPHA-trichloromethane and arsenazo Ⅲ, PMBP-benzene and arsenazo Ⅲ, respectively. The results are summarized as follows:
