Doc. No. 9.] 83 



policy adopted in the government of the placers, is equally applicable and 

 should be extended to them. 



. 



The following pages will contain a brief notice of some of the principal 

 mines of the State with a list of those in successful operation and their lo 

 cations. Also a table of Barometric Altitudes ; and Catalogue of Minerals 

 obtained during the tour, to be placed in the State Cabinet. 



LA FAYETTE AND HELVETIA MINE. 



This company is located at Grass Valley, Nevada County, and the sketch 

 of the workings of their mine is taken from the La Fayette Hill vein only 

 about two miles south-west of the town. The length of the vein at the 

 above hill is eleven hundred feet ; it has a curvilinear course, varying from 

 north-east -to south-west ; its mean, however, when marked on a right line 

 is north, ten degrees east. The dip of the vein is forty-one degrees east, 

 having a power of three feet at the depth of thirty-four feet ; at this point 

 the ore was of a poorer quality than at any other point. The depth of the 

 present working is about 55 feet, and here the vien increases in power and 

 value, being equal to three feet eight inches, and yielding in a large amount 

 of ore, forty dollars per ton. The vien, when discovered, was covered with 

 yellow r brown alluvium for five feet, and passed through this and decom 

 posed granite of a purple color fifteen feet, when it entered a mass of de 

 composed and fragmentary greenstone of five feet depth, thence into com 

 pact rock of the same character and continued to the depth of fifty-five 

 feet. 



Adit level is 1100 feet in length, exclusive of tram road for conveying 

 ore and attle from the mine ; it extends through the whole length of their 

 claim. At their present depth all the ore is obtained by blasting, which 

 adds much fo the expense of the mine. The cost of obtaining ore from this 

 mine is from seven to eight dollars per ton at present rates of labor. The 

 company have about 900 feet of vein in Gold Hill, which requires no blast- 

 inging and is obtained at the mill for five dollars per ton. 



The La Fayette Hill vein was much decomposed for the depth of thirty 

 feet, and contained a large quantity of peroxide iron and free gold ; after 

 passing into the compact greenstone the vein becomes quite firm, and highly 

 charged with pyrites investing gold ; the crystals were white and well-ter- 

 inmated, generally perfect in form. In some parts of the mine, galena is 

 met with and gold imbeded in it ; an examination of this latter mineral has 

 not been made for silver, but from its appearance it is quite probable that 

 it contains this metal. The matrix of the ore is a bluish white and trans 

 lucent, in pieces of one inch in thickness ; the blue tint of the vein in the 

 vicinity of the shafts is due in a great measure to finely divided particles of 

 lead. 



The capital of this company is about three hundred thousand dollars, and 

 their receipts in four months has been as high as $98,000, but their aver 

 age is tiear $10,000 per month ; the mine has yielded with great uniformity 

 since the commencement of operations, and- bids fair for future success. 



This mine has two Batteries and when in full operation is capable of re 

 ducing forty tons of ore per day, but one battery is run at a time as the 



