4:28 Turner — Rocks and Minerals from California. 



the south fork of the Stanislaus River and the Ham and 

 Birney gold mine on Five Mile Creek, which is a branch of the 

 south fork of the Stanislaus. Mr. Sharwood also found tel- 

 lurium in a cavity in a fragment of unrounded coarse gold 

 washed from gravel. This specimen is said to have come from 

 Big Creek, Butte County, California. 



7. Carbonaceous Material in Quartz. 



Many of the veins of the Gold Belt region of the Sierra 

 Nevada in the older rocks that lie east of the Mother Lode, are 

 composed of quartz which is dark in color. The coloring 

 material is so finely disseminated that a microscopic study of 

 the slides of this dark quartz gives no clue to the nature of the 

 coloring material. A specimen of this quartz from the Star 

 Gold Mine on Rose Creek, which is a branch of the Stanislaus 

 River, in Tuolumne County, was therefore selected for a chem- 

 ical examination. The quartz was examined by Dr. H. 1ST. 

 Stokes, who reported "that the coloring matter is carbonaceous, 

 not graphitic. Eight grams of the quartz, after the separation 

 of sulphides, were treated with HF. This left several milli- 

 grams of carbonaceous residue, the nature of which was con- 

 firmed by conversion into BaC0 3 ." The Star Gold Mine is in 

 Paleozoic rocks, the Calaveras formation of the Gold Belt 

 folios. 



8. Berthierlte. 



On the southwest slope of Mt. Gibbs, which is south of Mt. 

 Dana in Tuolumne County, in an area of schists, are some 

 heavy ledges of dark ore which have been exploited for silver. 

 A specimen of the ore from one of these ledges was submitted 

 to Prof. Munroe of the Columbian University in Washington 

 for assay. The returns gave only a trace of gold and one and 

 one-half ounces of silver per ton. This ore is therefore of no 

 economic value. Some blow-pipe tests made by Mr. Steiger, 

 under the direction of Prof. F. W. Clarke, showed that the ore 

 contains iron, antimony and silver. Prof. Clarke surmised that 

 the mineral berthierite might be present. More of the mate- 

 rial was examined by Dr. H. N. Stokes, who reported : 



u No. 879 S. N. is possibly berthierite, as it contains a large 

 amount of iron, which dissolves together with the sulphide of 

 antimony in cold strong HC1. The mineral is so impure, how- 

 ever, that it cannot be asserted positively that this iron does 

 not come from some other iron mineral soluble in HC1. It is 

 full of pyrite, galena or some other sulphide containing lead, 

 as well as quartz and other minerals too intimately mixed to 

 admit of separation. For this reason a quantitative analysis 

 does not seem likely to give any definite results." 



U. S. Geological Survey, Washington, D. C. 



