. Transactions . on of the garnet and magnetite zones. That theselatter rocks were produced by the hot water gases and watercarrying dissolved mineral derived from the eruptives, reachingupon the adjacent limestones through replacement and recom-bination, can hardly be doubted. The Emma Mine. 191 It is seen from the analyses of the ore that the sulphur presentis very small, barely more than sufficient to form the copperpyrites present. Iron sulphides are of rare occurrence, and it seems certainthat the magnetite was deposited as such, and did not resultfrom the alteration of sulphides. This vi
. Transactions . on of the garnet and magnetite zones. That theselatter rocks were produced by the hot water gases and watercarrying dissolved mineral derived from the eruptives, reachingupon the adjacent limestones through replacement and recom-bination, can hardly be doubted. The Emma Mine. 191 It is seen from the analyses of the ore that the sulphur presentis very small, barely more than sufficient to form the copperpyrites present. Iron sulphides are of rare occurrence, and it seems certainthat the magnetite was deposited as such, and did not resultfrom the alteration of sulphides. This view is borne out by thefact that as a rule magnetite cr^stals and not iron sulphides arefound in the garnet zone, however far removed from the main body ofmagnetite. The crystalline limestone found next the magnetitein the mine is considerably purer than the main portion of thelimestone formation. The accompanying photographs of rock sections from theEmma throw an interesting light on the formation of the Fig 1. Fig. 1 is a specimen of garnet ore, and shows a limestone in thecourse of alteration to a garnet rock. Some calcite remains, butit has mainly been replaced by garnet together with a little pyrites run through the mass in irregular strings andbunches, and there are also some bits of magnetite. Fig. 2 represents a rock from the 150 ft. level, in which all theoriginal mineral has been replaced by plagioclase, feldspar and 192 The Canadian Mining Institute,
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