880 PROCEEDINGS OP THE CALIFORNIA 



detected the foliated tellurium in extremely minute quantity in one of the mines 

 at Angels, and I mentioned in a publication, in 1864, its probable occurrence 

 among the ores of the Josephine and Pine Tree Mines of Mariposa. A careful 

 scrutiny will probably detect those compounds of tellurium at other points when 

 the mother vein is opened, as at Blue Gulch, Quartz Mountain, and Whisky Hill. 

 I have already recognized the blackish antimonial copper sulphides at the App 

 Mine and Silver's Mine, and in the croppings on the surface of Whisky Hill. 

 Indeed it may not be too much to state that these ores appear to be somewhat 

 characteristic of those portions of the mother vein occurring south of Angels, 

 and especially wherever it is inclosed in magnesian rocks. 



Genth has named a species Melonite, from Melones Mine, which he says is a 

 telluric] of nickel. I have not been able to recognize this compound among 

 those ores of the Melones, which I have seen. 



(b.) Some Mineralogical Features of the Mother Vein. — From the 

 opportunity I have had of studying the mother vein, I arrive at the general 

 conclusion that its mineralogical characteristics vary greatly with the chemical 

 constitution of the rocks which inclose it. Wherever the serpentine or talcose 

 and calcareous rocks from the inclosing walls, or are near it, the mineral con- 

 tents of the vein are essentially different from those observed where the inclosing 

 rocks are argillites, or syenites and diorites. 



These we find at Mariposa, in the Josephine and Pine Tree Mines, at Perion 

 Blanco, Maxwell Creek, Blue Gulch, Quartz Mountain, Silver's, Whisky Hill, 

 Rawhide, Chapavele Hill, Carson Hill, Angels, and Placerville — at ali which 

 places I have examined the mother lode with more or less care — a peculiar light 

 apple-green mineral, occurring in scales, associated with iron pyrites in small 

 and brilliant pentagonal dodecahedrons and implanted in a gangue of dolo- 

 mite mingled with quartz. The dolomite is of the variety known as ankerite, 

 and by its decomposition, which seems hastened by the oxidation of the associ- 

 ated pyrites, gives origin to those highly characteristic masses of brown and 

 reddish-yellow iron gossan which form the characteristic feature of the out- 

 croppings of those portions of the mother vein just enumerated. These gos- 

 sans always retain the bright green mineral before alluded to unchanged, as 

 also cellular quartz which discloses in its rhombic cavities the form of the 

 decomposed crystals of dolomite or ankerite whose removal has left the vacant 

 spaces. Before decomposition this triple carbonate of lime, magnesia, and iron 

 is brilliantly white, and its real chemical character would never be suspected. 



The green mineral, so far as I can ascertain, has never been described, 

 although it has often been noticed. It has been called by some, nickel gymnite, 

 and I have once distinguished it by this name in a mining report. But this is 

 a misnomer which I take this occasion to correct ; iik kel gymnite of Genth, 

 found at Texas, Penna., is a hydrous silicate of magnesia, lime, and nickel. The 

 species so characteristic of certain portions of the mother vein is anhydrous, 

 and contain no nickel. 



Mariposite (Provisional Name). Before the blowpipe it yields evidence of 

 the presence of the protoxides of iron, lime, magnesia, and potassium ; of the 



