Hiroshi Hamaguchi

Values for trace elements in G-1 and W-1 with neutron activation analysis

Trace elements were determined in Japanese granite (G-1) and basaltic (W- 1) rocks by neutron activation analysis. The elements determined are antimony, arsenic, copper, europium, gold, lanthanum, samarium, scandium, and uranium. The results are compared with previous determinations. (N.W.R.)

Silver content of igneous rocks

Abstract The following averages of silver for various types of Japanese igneous rocks have been obtained (in p.p.m.): granites 0.0037, granodiorites 0.050, liparites 0.049, quartz diorites and diorites 0.053, silicic andesites and andesites 0.080, basalts 0.11, diabases 0.12, gabbros 0.11 and ultramafic rocks 0.060. The crustal abundance of silver is estimated to be 0.08 p.p.m.

Ultraviolet spectrophotometric determination of scandium with tiron

Abstract A method is described for the spectrophotometric determination of 3–250 μg of scandium with tiron. The molar extinction coefficient of scandium in an acetate buffer (pH 6.0) is 8 × 10 3 at 310 mμ. Small amounts of aluminium, titanium, iron, cerium, molybdenum, thorium and zirconium seriously interfere. Organic anions such as oxalate, citrate, tartrate and malate form complexes with scandium. Both 1:1 and 1:3 complexes of scandium with tiron are suggested.

The distribution of minor elements in the rocks of Sakura-jima volcano

Abstract Geochemical and crystallochemical relationships in the lavas and pyroclastics of Sakura-jima volcano, Japan, suggest that magmatic differentiation is the dominant fractionation process. A triangular diagram is shown for Na-K-Ca and total Fe—Mg—Na + K. The volcanics investigated are the Kitadake, Minamidake, unknown eruption epoch, 1468–1476, 1779, 1914, 1946 flows, and 1955–1958 pyroclastics. Trends are illustrated in Cr, Mg, Ca, V, Fe, Si, Al, Ga and O in modified Larsen diagrams. Various ionic ratios, especially V/Fe, show marked variation on the modified Larsen plot. From the 1468–1476 until the 1914 eruptions, the Sakura-jima lavas tend to become more mafic. From 1946 until 1958, there is a tendency to become more silicic. However, within the 1955–1958 volcanic sequence, Co, Cr and V increases suggest increasing mafic differentiation of the lavas and pyroclastics. Distinct and extreme anomalies occur in Co, Cr and V in the initial pulse of a given eruption within the 1955–1958 sequence. During the initial high energy eruptive phase, expulsion of mafic differentiates (enriched in Co, Cr, and V) consolidated in the volcanic throat is thought to account for these high concentrations. Pb is also enriched in the early eruptive phases in the 1955–1958 volcanic series. Volcanic sublimates accumulating during the inter-eruptive period in the pyroclastic material within the volcano may account for this phenomenon. Spectroscopic analyses for Ga, Ni, Co, Cr, V, Pb, and Sn are given for sixty-two samples.

Spectrochemical Analyses of Silicate Rocks by Means of Rotating Logarithmic Sector Method

従来,微量元素の地球化学的研究においては,その迅速性,簡便性の故を以て,孤光スペクトルによる分析法が広く用いられている.併しながら,多数の元素を同時に定量することは,孤光中における各元素の分別的蒸溜現象のため,かなりの困難が伴う.Goldschmidt,Sahama,Mitchell等の広汎な地球化学的研究においても,ある程度精度を儀牲にして,内部標準法によらない半定量法が用いられている.Brayの方法では,塩化パラジウムを内部標準とする方法が採用されているが,中型程度の分光器しか使えない現状においては,そのまま採用し難い.内部標準法を用いる場合には,各元素の揮発度に応じて,数種の内部標準が併用されることが望ましいが,筆者らは,塩化ナトリウムを分光学的緩衝剤として添加することにより,ビスマスを内部標準として珪酸塩岩石中の鉛,錫,ゲルマニウム,ニッケル,コバルトを同時にかつ迅速に定量することが出来たので,その詳細に関して述べる.