202 W. Lindgren — Auriferous Veins of California. 



dolomite or calcite,* contain free gold besides sulphides, and 

 occur in the sedimentary auriferous slate series or in the erup- 

 tive bodies, unaltered or dynamo-metamorphosed, which are 

 connected with them; the large granitic areas are usually 

 barren. The group of veins to be described here shows thus 

 a type which in many respects differs from the ordinary. In- 

 deed, auriferous deposits of this class do not appear to have 

 been mentioned as occurring in any other part of the United 

 States. 



Location and discovery. — The Meadow Lake mining dis- 

 trict is situated in Nevada County about ten miles north of 

 Cisco, a station on the Central Pacific Kailroad at elevations 

 ranging from 7000 to 7500 feet. The first divide of the Sierra 

 Nevada whose summits here reach 9000 feet, is only eight 

 miles distant towards the east. The climate is severe and 

 snow sometimes falls to a depth of twenty feet on the level. 

 A rough trail leads into the district from Cisco ; a wagon road 

 thirty-five miles long leads to Truckee by a circuitous route. 



The mines were discovered in 1863 by H. H. Hartley, and 

 a great rush took place to the district in 1865 and 1866. The 

 free gold found at the surface soon gave way to relatively 

 poor sulphides and the boom speedily collapsed. At various 

 times subsequently some work had been done on the principal 

 mines and only recently the deposits have been subject of some 

 discussion in the technical papers. Considering the difficulties 

 of access and climate, there is some doubt as to whether any 

 of the deposits can ever be worked with profit. The ores will 

 not average more than from seven to ten dollars per ton at the 

 most. Probably $200,000 or $300,000 have been expended in 

 the district, while it is doubtful if more than $75,000 have 

 been taken out. 



General Geology.— -The area shown in the sketch map (p. 204) 

 is of a rough mountainous character, the elevations ranging from 

 5,800 to 7,800 feet. The vegetation is scant, the soil having 

 been swept away by the Pleistocene ice sheet once covering 

 the region, leaving enormous bare expanses of the prevailing 

 granitic rock. 



Granodiorite. — A. light gray granitic rock occupies the 

 larger part of the area of the map and in it is contained 

 nearly all of the veins. The rock is in general identical with 

 the gray so-called granite that occupies such large areas in the 



* In a footnote in an article on " The GTold deposit at Pine Hill " (this Journal. 

 August, 1892) regarding gold in calcite and dolomite I omitted to mention that 

 such occurrences had first been noted by Prof. W. P. Blake from Mariposa and 

 Amador Counties, Cal. Annot. Catal. on the principal mineral species of Cali- 

 fornia." Sacramento, 1866. 



