The deposits of the useful minerals & rocks; their origin, form, and content . nd sometimesan aplitic character. According to Krusch, on the other hand, the biotite-gneiss is a pressure-deformed granite which has assumed a fibrous, gneiss-like structure; in many places it merges into granite. It contains inaddition large and small amphibolite inclusions, which are resorbed alongtheir outlines. The gneiss, gneiss-granite, and amphibolite, are all traversedby aplite. In this rock complex a number of fissures occur, which generally strikeeast-west, dip some 60°-70° to the north, and are arranged
The deposits of the useful minerals & rocks; their origin, form, and content . nd sometimesan aplitic character. According to Krusch, on the other hand, the biotite-gneiss is a pressure-deformed granite which has assumed a fibrous, gneiss-like structure; in many places it merges into granite. It contains inaddition large and small amphibolite inclusions, which are resorbed alongtheir outlines. The gneiss, gneiss-granite, and amphibolite, are all traversedby aplite. In this rock complex a number of fissures occur, which generally strikeeast-west, dip some 60°-70° to the north, and are arranged in systems. THE OLD GOLD LODES 635 These fissures have generally a width of but a few millimetres, seldomcentimetres, and are filled with quartz and pyrite. On either hand analteration of the granite has taken place, this being chiefly in the form of animpregnation with quartz and pyrite. Though these fissures are in generalparallel along the strike they often intersect in dip. In addition, numerousintersecting veins similarly filled proceed from the fissures and traverse. Fig. 326.—The gold lodes at Roudiiy. Krusch, Zeit. d. d. geoL Ges., 1902. the granite, the felspar of which is sometimes kaolinized and sometimes,as is also the case with the biotite, replaced by quartz and pyrite. By this far-reaching silicification and pyritization the granite zonesin which the fissures occur have become altered to pyrite- and quartz-impregnated zones, such zones being mined as single occurrences ; theyhave as a rule no sharp boundaries against the normal such zones are known, these from north to south being the Joseph!lode, the Main lode, and the Branch lode. These dip steeply to the northand vary considerably in width, this dimension sometimes reaching as 636 OEE-DEPOSITS much as 20 metres. Continued towards the east, as illustrated in Fig. 326,they unite to form one deposit. The gold content of these veins and impregnation zones is chieflyassociated -nith the pyr
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
