FINENESS OP THE GOLD. . 249 



stream. Only about 25 cents and $1 were obtained by these tests. After- 

 ward they put in a wing- dam just above the area I had sluiced out, and 

 found a few square feet of the clay-gravel, but above that the bed-rock 

 pitched up stream and changed to a hard quartzite, with loose, poor gravel. 

 The result of about six hours' work was $2.70 gold, mostly obtained from 

 the small quantity of clay-gravel adjoining my pit. No one attempted to 

 follow this deposit far into the flats on the banks of the stream, though it 

 gave equally good results at either end, and may have been continuous for 

 some distance across the bottom. In review of this deposit, it may be 

 described as a strip of j)lastic clay crossing the bed of the creek, and result- 

 ing from the decomposition of a strata of soft clay- slate located on the rise 

 of the bed-rock, while both above and below was a hard massive quartzite, 

 smooth and water-worn, but protecting the slate from being rapidly cut 

 away by the current of the stream. The sample of gold obtained by this 

 test was submitted to Mr. Ricketts, assayer at the School of Mines, New 

 York, for the determination of its fineness and value per ounce. The 

 results of two assays, each made in duplicate, are annexed, showing that 

 the gold from this district is very pure, being 946-fV fine, or 22f carats, and, 

 just as it is washed from the placers, is worth $19.44 to $19.63 per ounce. 



Certificate of assay. 



School of Mines, 

 New York, January 6, 1876. 

 Sir : The sample of placer gold from Spring Greek, Black Hills of Dakota, sub- 

 mitted to me for examination, contains, by assay of raw dust without previous melting — 



Gold.... 937.8 fine. 



Silver 45. 9 fine. 



Base metal 16. 30 



Total 1000. 00 



The excess of base metal is due to the presence of oxide of iron adhering to the 

 particles of gold. 



The value in gold coin of one ounce troy of dust is — 



Gold $19. 384 



Silver 0.057 



Total 19.44 



Very respectfullv, 



P. De p. eicketts, e. m. 



Walter P. Jenney, E. M. 



