Transactions . ck to the distinctly brecciatcd fault-material,and its plane is often oc-cupied by a thin Beam offibrous gypsum. The fault-material, orrock-mass comprised be-tween this hanging-wallfissure and the limestonefoot-wall, is of a variednature. On the hanging-wall side, especially 1ST. ofthe shafts, it is recogniz-able as altered igneousrock; near the foot-wall,on the other hand, thereis much more or lessaltered limestone; butthe greater part of themass is so changed thatits original charactercannot be , W. of the old shafton the 7th level and ad-joining the caved groun
Transactions . ck to the distinctly brecciatcd fault-material,and its plane is often oc-cupied by a thin Beam offibrous gypsum. The fault-material, orrock-mass comprised be-tween this hanging-wallfissure and the limestonefoot-wall, is of a variednature. On the hanging-wall side, especially 1ST. ofthe shafts, it is recogniz-able as altered igneousrock; near the foot-wall,on the other hand, thereis much more or lessaltered limestone; butthe greater part of themass is so changed thatits original charactercannot be , W. of the old shafton the 7th level and ad-joining the caved ground(see Fig. 9) is a body ofmuch shattered horn-stone-like chert (calledby the miners rhyolite)which is here only about15 ft. thick, but increasesto more than 100 ft. inthe lower levels. Only portions of thefault-zone are mineral-ized ; but it was not possible to determine the outlines of theore, first, because of the great cave in the main ore-body, ex-tending from the surface down to the 7th level, which the ©. mi: DBL LM \i: \M» IH1 HORH-SILVM MH (581 drifts run bj the present management have been obliged tavoid; and, Becondly, because the paj ad< - off into mate- rial which, though mineralized, La too low in grade to beworked at present, and is not recognized as ore. The greatore-shoot, or main ore-body, followed from the Burface down-wards, appears to have had a general pitch B. and E., ami tohave become very much attenuated, both in size and value inthe lower levels below the 7th. It was probably the variationsin this body that were referred to when it was said that thewalls have come together twice in a vertical depth of L200 ft. The point of greatest interest developed by my visit was thedistribution of the metal- within the genera] mineralized observed above, neither copper nor zinc were found in theupper part of the ore-body. Zinc came in in small amounts ttered through the re in the 5th level, and increased down-wards until at the 7th level there is an en
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
