Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Bromine to Chlorine Ratios in Igneous Rocks
Tsutomu Sugiura
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1968 Volume 41 Issue 5 Pages 1133-1139


Samples were decomposed by fusion with Na2O2 and benzoic acid in a Parr-bomb, then halogens were separated from other elements by distillation and determined colorimetrically; chlorine by the thiocyanate method and bromine by the rosaniline method. The chlorine and bromine contents of rocks cover a very wide range with no relation to the type of rock. The Br/Cl ratio, however, is in a relatively narrow range from 1×10−3 to 16×10−3 by weight, mostly from 1×10−3 to 6×10−3, and evidently lower than those reported by previous investigators. The average Br/Cl ratio is (3±2)×10−3, about one-seventh of the value generally accepted for igneous rocks. The halogen content of quartz and feldspar is usually so small that it was not usually determined. The Br/Cl ratio in biotite seems to be rather small and Qertainly is smaller than 3×10−3 on the average. The Br/Cl ratios in volcanic rocks are similar to those in volcanic gases for any one volcano studied.

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