28 LeConte and Rising — Metalliferous Vein-fi 



particles. Pyrites is also found in notable quantities both in 

 the rubble-mud and in the bounding rocks on each side, espe- 

 cially in the more porous sandstone. The same rubble stratum 

 can be traced out-cropping on the surface farther east beyond 

 the limits of the lava-flow, and is there also the seat of solfataric 

 action, and has been worked for cinnabar. The question of 

 the origin of this rubble-mud stratum will come up for discus- 

 sion hereafter. 



Completer examination of the strata beneath the lava.— The above 

 is a brief description of the phenomena as seen during our 

 earlier visits. In the summer of 1881, we again visited the 

 mines, and in addition to complete confirmation of previous 

 tad an opportunity, never enjoyed before, of examining 

 the stratified rocks underlying the lava to a depth of 260 feet. 

 Since our previous visit in 1880, the very intelligent Superin- 

 tendent, Mr. Fiedler, had sunk a shaft some distance to the 

 south of the " "Wagon-spring cut," and about 150 feet outside 

 the limits of the lava-flow, with the intention of reaching the 

 vein by drifting under the lava on several different levels. 

 The upper one of these drifts, viz : the 210-feet level, had 

 already been pushed 150 feet in the direction of the " Wagon- 

 spring cut," but had not yet quite reached a point direct ly 

 beneath it. The phenomena observed are as follows : for 70 

 or 80 feet from the shaft the rock is barren sandstone and shale 

 dipping to the south and comparatively dry and cool. Then 

 the rock becomes shattered or brecciated and highly charged 

 with up-coming hot water containing large amount of alkaline 

 sulphides, with excess of C0 3 and H 2 S. In the hottest places 

 the temperature of the water is 160° and the C0 3 bubbles up 

 so profusely that a lighted candle near its surface is quickly 

 extinguished. The heat of the freshly cut rock is often too 

 great to be borne by the naked hand. In this hot shattered 

 rock is found the ore. The mine is worked with difficulty on 

 account of the almost insupportable heat. This difficulty has 

 now been largely removed by the more complete ventihition 

 -'■ '*;queiitl\ , troduced. The lower-level drift had not at 

 the time of our visit yet reached the ore- body.* 



Description of the ore-bodies.— The brecciated layer which 

 forms the water-way, is here, as in the wagon-spring cut, com- 

 posed of fragments of sandstone and shale, mostly angular but 

 sometimes sub-angular, as if the edges had been either worn 

 away or else dissolved away. In some places, where the up- 



