456 



Hillebrand, Turner and Olarke- 



-RosGoelite. 



found interstratih'ed with the roscoelite laminae in pieces from 

 the value of one dollar to the minutest microscopic particles. 

 He also states that from four to five hundred pounds of ros- 

 coelite were obtained by the miners, all of which was wasted in 

 extracting the gold. 



Mr. George W. Kimble of Placerville, California, for many 

 years county surveyor, has furnished the California material 

 analyzed by Dr. Hillebrand as well as other specimens. In 

 these specimens the roscoelite is in part embedded in quartz 

 and probably contemporaneous in formation with the quartz, 

 and in part fills little cracks in the quartz and therefore some- 

 what later. 



There are given below four localities where roscoelite has 

 been found, according to Mr. Kimble, to whom the author is 

 indebted for the following information about the occurrence of 

 the mineral at these localities. 



/ 



^Thory&nn. Hill - , V 



daAO.ver&s $ oy ma.*-; oi\, Serptntint. ^r a.r\o<* ior\t e - 



Fig. l. Geological map copied from the Placerville folio, showing roscoelite 

 localities. Geology by W. Lfndgren. 



The accompanying map, on the scale of about 1-150000, gives 

 the exact localities where the roscoelite has been found. The 

 Calaveras formation is largely of Carboniferous age, as may 



