File:Transactions (1895) (14781871511).jpg

Identifier: transactions05cana (find matches)
Title: Transactions
Year: 1895 (1890s)
Authors: Canadian Institute of Mining and Metallurgy
Subjects: Mineral industries Mines and mineral resources
Publisher: Montreal (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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uld be the line of contact. We might alsotake into account the principle of convection currents which would benaturally set up in the mass by the differentiation in temperature of thedifferent parts of the molten magma. These, as they passed along thecolder surfaces of the walls inclosing the mass would coat them withthe sulphides, which being the earlier and less mobile crystallizationswould be the first to crystallize out of any molten magma. The foregoing would of course not hold were the granites andgneisses which have been found in nearly all cases to bound thegreenstone near the deposits, proven to be of younger age than thegreenstone. We should then have to explain the deposits as havingtaken their present form subsequent to the eruption of the green-stones. That the granites and gneisses are younger in many cases atleast, is proven by their cutting into the greenstones in the form ofstringers or small dykes near the junctions. The Sulthide Ore Bodies of the Sudbury Region. 541
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542 The Canadian Mining Institute. Such is found to be the case near the Murray mine and severalother locahties in the district. The younger age of these granites andgneisses is now admitted by all authorities on the subject, still, somewho have admitted it do not seem to have recognized the fact that,this being so, the deposits cannot have been formed along the contactswhile the greenstones were still molten, as they intimate. In somecases cracks and cleavage joints in the greenstone are filled with thinseams of mineral matter pointing undoubtedly to aqueous action ;while also the granites and gneisses near the contacts are sometimesfound to contain specks of the sulphides. These facts, in conjunctionwith those pointed out in former parts of the paper, have caused thewriter to form the opinion on the formation of the veins which hestated in the third theory. In the writers opinion, such a theoryviolates no known laws, and harmonizes more with most of theprinciples which have been dis

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