480 GEOLOGY AND MIXIXG INDUSTRY OF LEADVILLE. 



the middle of the claim from the bottom of No. 1 shaft to 160 feet beyond 

 the bottom of No. 3 shaft. At No. 1 shaft, and for 40 feet north of it, it 

 runs in White Limestone, dipping 20 northeast, which is more or less 

 stained, and occasionally replaced by clayey iron oxide. It then runs into 

 decomposed and iron-stained porphyry, which is in places so laminated that 

 it might be mistaken for a shale. The Parting Quartzite, which is disinte- 

 grated and contains thin layers of bluish shale, comes in at 1 60 feet from 

 No. 1 and continues for 100 feet, lying nearly horizontal, and probably 

 represents a minor roll in the formation, as shown in Section D. Beyond 

 No. 2 shaft the quartzite gives way to compact White Porphyry, in which 

 a cross-cut to the east shows the iron body resting on it and dipping east- 

 ward. At the bottom of No. 3 shaft the Parting Quartzite is again cut, 

 here being above the White Porphyry and immediately under the iron 

 body or ore horizon. The drift then runs for 80 feet through the iron body 

 and suddenly passes into decomposed Blue Limestone, which, on the sides 

 of the drift, has all the appearance of the solid unaltered rock, showing the 

 stratification planes dipping northeast at 40, the characteristic ribbings of 

 white spar, and an occasional fossil resembling a Euomphalus, but which 

 when taken into the hand immediately crumbles into fine lime-sand. A 

 partial analysis of this lime-sand is given in Appendix B, Table VI, which 

 shows it to have the normal proportions of lime and magnesia contained 

 in the unaltered, rock. Toward the end of the drift the dip shallows, prob- 

 ably because it is becoming more nearly parallel with the strike of the 

 beds. At the very end the roof of the drift has caved, showing decomposed 

 White Porphyry immediately above the limestone and Wash a little distance 

 above that This point, it will be observed, is almost opposite the workings 

 of the Virginius claim. Beyond it the ore horizon has not been explored, 

 nor is it likely to be until powerful pumping machinery is introduced capa- 

 ble of controlling the great influx of water. 



Matchless. The Matchless ground, which lies next east of the Dunkin 

 claim, has been relatively little explored, probably because in early days 

 it was considered unpromising ground, since the few prospecting shafts that 

 were sunk did not strike rich ore. The indications afforded by the map, 

 which show the condition of explorations at the time of this examination, 



