326 Mr. J. A. Phillips's Notes on the Chemical Geology 



nity of certain coloured streaks, generally nearly parallel with 

 the apparent lines of deposition of the quartz. When gold is 

 found lining a cavity in a lode, or is enclosed in plastic clay, it is 

 often in the form of crystals, which are usually cither octahedrons 

 or cubes modified by planes of the octahedron or rhombic dode- 

 cahedron. When crystallization takes place in a narrow fissure, 

 the crystals are much flattened. 



In one of the detrital beds in the vicinity of the village of 

 Volcano, in the county of Amador, a distinctly marked quartz 

 vein may be observed cutting through the gravel, and evidently 

 formed by the action of water holding silica in solution. The 

 mass of this lode consists of agate and chalcedony, portions of 

 which are coloured by ferruginous stains. In speaking of this 

 vein, Professor Whitney says, " This is not by any means an 

 isolated case; other localities have been noticed where all the 

 conditions necessary to the formation of quartz veins, similar in 

 their general features to those in the auriferous slates, must have 

 existed during the most recent geological epoch." 



With reference to this subject, Dr. Oxland"* writes me as fol- 

 lows : — " The recent quartz vein containing argentiferous pyrites, 

 of which I spoke to you when we met in California, is situated 

 at Sulphur Springs, Bear Valley, about ten miles north-east of 

 Borax Lake. This locality is resorted to by invalids for the pur- 

 pose of bathing in the hot waters, which are supposed to possess 

 medicinal properties, and which flow in very considerable quan- 

 tities out of the foot of a hill on the north side of the creek. 



" This water, which contains carbonate of soda, chloride of 

 sodium, and a little borax, is perfectly bright and clear, but so 

 hot, that it has to be conducted into a large reservoir to cool 

 before it can be admitted into the tubs provided in the wooden 

 bathing-sheds. 



" The hill out of which this hot water flows rises about 400 

 feetiabove the canon through which the waters make their escape, 

 and near its summit a deposit of sulphur has been opened 

 upon. This has been covered to a depth of several feet by vege- 

 table mould, and Manzanita bushes are now growing luxuriantly 

 upon it. In cutting a roadway from the valley to the sulphur 

 deposit, a vein of friable quartz, evidently due to the action which 

 has produced the solfatara, was cut through. This silica is 

 banded in the direction of the vein, and contains finely divided 

 iron pyrites. I took what I considered a fair sample of this 

 quartz, which afforded me 16 ounces of silver per ton. Many 

 of the nuggets of gold obtained in this immediate neighbourhood 

 have been found with large pieces of cinnabar adhering to them." 



* Formerly of the Toland Medical College, San Francisco, but now of 

 Plymouth. 



