ENDLICH.] 



GEOLOGY GUXNELL LODE. 287 



Following the example of the maiu lodes of this region, the chief ore 

 is pyrite and chalcopyrite, as seen in Plate III, but galenite and spha- 

 lerite begin to make their appearance in more connected quantities. 

 Quartz and feldspar compose the gangue-rock. Wherever granite forms 

 the one wall of a lode, the feldspathic compounds appear in greater 

 quantities in the ganguethanin other formations, or even in such where 

 the granite is hard and fine-grained. In that case the gangue is mostly 

 quartz alone, or the ore- veins are found to traverse the granite itself, 

 ■without any younger formation of gangue-rock appearing. 



Of minerals, only the four mentioned above are found, besides native 

 gold, Pyrite occurs here in cubical crystals as well as in dodecahedral. 



The Gunnell lode is situated on Gunuell Hill to the west of Cen- 

 tral, and has a strike of about east 8^ north. It has been one of the 

 most productive veins of that region, and is supplied with a number of 

 shafts, the levels driven in the diiferent claims mostly connecting under- 

 ground. Of those claims located on this lode, the following were vis- 

 ited : Gunnell, Pippin, Coleman, and Peers. The latter had not reached 

 a depth of more than 120 feet at that time, and nothing but surface-ore 

 was obtained, while the shafts on other claims had been sunk much 

 deeper. The peers varied from 4 to 5 feet between walls, with a body 

 of ore 6 inches to 2 feet thick, mostly decomposed pyrite. 



On the Pippin claim, the shaft has reached a depth of about 415 feet, 

 and a number of levels have been worked out on either side. Along 

 its entire length, the Gunnell runs in gneiss, modified somewhat in tex- 

 ture and structure, so as to be termed a granitic gneiss. It has clean, 

 well-defined walls, with a slight dip to the south, varying in different 

 parts of the mines. A number of small veins, from mere seams up to 

 more than half a foot, run into the main vein, in two instances travers- 

 ing it, but apparently extending only a short distance on either side. 



Scarcely any difference can be observed in the character of the ore 

 from that of other mines previously described, except the presence of 

 greater quantities of chalcopyrite. Pyrite has a tendency to accumulate 

 in long sheets in several horizons throughout the vein of the Pippin 

 claim, which measures, on an average, 4 feet in thickness. As usual, the 

 gangue is composed of quartz, having, however, far less feldspar 

 than in those veins that are in contact with granite. 



Of minerals, the following were found in this mine : Pyrite, chiefly 

 massive, otherwise in cubical crystals, in distinction to the more cen- 

 trally located mines, where they are dodecahedral ; chalcopyrite, sphal- 

 erite, galenite, melaconite, (as a result of the decomposition of chalcopy- 

 rite,) quartz-crystals, and native gold. In the gangue, quartz, feldspar, 

 and some talc were contained. 



A shaft of about 250 feet in depth has been sunk on the Coleman 

 claim, to which almost all the characteristics given for the Pippin will 

 apply. Between walls, the vein is a little thicker here than in the Pip- 

 pin, averaging from 5 to 6 feet. At a depth of 240 feet, a cross-section 

 of the vein was taken, which can give an idea of the distribution of the 

 ore, (Plate III.) On either side, nearest to the wall, is a very consider- 

 able segregation of pyrite, intimately associated with chalcopyrite, and 

 interspersed with grains and threads, even small massive quantities of 

 sphalerite and galenite. Next to that, toward the center, quartz sets 

 in — a light-gray to white quartz — containing, disseminated all through it, 

 numerous small particles, mainly of pyrite, but also of the other miner- 

 als occurring. In this mine there is but very little dip noticeable in 

 the vein, which is bordered by clean walls. Its minerals are identical 

 with those of the Pippin. In all its parts, the Gunnell shows a very 



