The deposits of the useful minerals & rocks; their origin, form, and content . is difference being probably referable to the differentcharacter of the two rocks. The Birkenberg lodes, occurring chiefly inthe first sandstone zone, extend to the clay-parting, beyond which, asillustrated in Fig. 341, they continue in the slate in the hanging-wall ofthat parting. In the second sandstone zone no lodes at present are beingworked ; such as there are contain poor ore, that is, sphalerite, galena, anda little tetrahedrite, with quartzose gangue, in disconnected ore-bodies. 1 Diirrerz,VOL. II O 708 OEE-
The deposits of the useful minerals & rocks; their origin, form, and content . is difference being probably referable to the differentcharacter of the two rocks. The Birkenberg lodes, occurring chiefly inthe first sandstone zone, extend to the clay-parting, beyond which, asillustrated in Fig. 341, they continue in the slate in the hanging-wall ofthat parting. In the second sandstone zone no lodes at present are beingworked ; such as there are contain poor ore, that is, sphalerite, galena, anda little tetrahedrite, with quartzose gangue, in disconnected ore-bodies. 1 Diirrerz,VOL. II O 708 OEE-DEPOSITS Concerning the silver content of the galena, Hofmann has publishedmuch detailed information.^ It was formerly supposed that the silverin the Adalbert main lode between surface and depth increased from 0-07to 0-7 per cent, equivalent to 0-063 per cent per 100 metres. The morecareful determinations of Hofmann upon clean material have however Section shelving relation of greenstone dykes—hatched—to the ^z JosefJh ProAopSh OVJ*?*. LeveJ U + 18S Sea Level 26- Z65}- Intersections of the lodes with the clay-parting, projected on the plane of that Lodes in the hanglny-uxM slate. 31. level. Distances followed in theslate, given in inches.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
