356 University of California Publications. [Geology 



and south trend and is best seen in a tunnel which has been 

 driven on the west side of the gulch ; a third lies about 400 yards 

 west of Copper Flat and appears to be a spur or branch from 

 the main White Hill fault already noted; a fourth lies about 

 800 yards northwest of the Saxton mine and brings the Ruth 

 limestone in abutment upon the White Pine shale and a similar 

 fault occurs on the north side of Lane City. 



MINERALOGY OF THE DISTRICT. 



In addition to the minerals enumerated in the petrographical 

 descriptions of the rocks of the district, the following minerals 

 have been encountered and are here summarily listed with brief 

 notes for convenient reference, in the expectation that the list 

 will grow larger as the district becomes better known. 



Pyrite in small cubes and pentagonal dodecahedra common 

 in the ore-bearing porphyry and minette below the zone of oxi- 

 dation. 



Chalcopyrite in nests and irregular masses usually associated 

 with garnet at the contact of the monzonite with limestone and 

 shale and in the quartz blout of the ore-bearing porphyry. 



Chalcocite the valuable copper ore of the district, and so far 

 as known confined to the ore-bearing porphyry below the zone 

 of oxidation through which it is disseminated in small grains. 



Native copper found rarely in the ore-bearing porphyry of 

 the Ruth Mine. 



Chrysocolla occurs to a limited extent in the ore-bearing por- 

 phyry and more abundantly in croppings of ore in isolated 

 bodies of quartz blout, and then associated with the carbonates 

 of copper. 



Azurite in the superficial or oxidized zone of the ore-bearing 

 porphyry at the Copper Flat mines and in various isolated crop- 

 pings of quartz blout. 



Malachite same occurrence as azurite. 



Chalcanthite as incrustations of current formation on moist 

 surfaces of the ore-bearing porphyry protected from the rain. 



Melanterite same occurrence as chalcanthite. 



OUvenite (?) a green mineral determined qualitatively as a 

 copper arsenate. A rare occurrence in the Ruth Mine. 



