E. MINERALOGY AND GEOLOGY. 93 



cofter-darn. According to Mr. Dubois, of the United States 

 Mint, this ore becomes richer with the increasing depth, and 

 is now yielding at the rate of $13,000 a ton. Pr. Am. Phil. 

 Soc, December, 1870. 



NEW MINERAL OIL LOCALITIES. 



An extensive bed of bituminous slate has been discovered 

 eighty miles from Sydney, Australia, near to the western 

 slope of the Blue Mountains, and a large establishment has 

 been erected for the purpose of obtaining oil. The seam is 

 'horizontal, and from five and a half to six feet thick, in strati- 

 fied sandstone. About one hundred tons of the slate are 

 worked up weekly. The crude oil first obtained is subse- 

 quently converted into burning-fluid, lubricating oil, etc. In 

 that portion of India, also, adjoining the mountains of Persia^ 

 principally occupied by the cretaceous and tertiary strata, 

 sufficient traces of petroleum have been found to make it im- 

 portant to make further investigations. Petroleum has like- 

 wise already been obtained in the vicinity of Gunda. 



NEW LOCALITY OF TIN. 



The attempt to discover tin in workable quantities in the 

 United States has been rather a failure, since, notwithstand- 

 ing the many enthusiastic announcements of the finding of 

 mines of this valuable metal in Missouri, Utah, and elsewhere, 

 it would appear that the metal itself is not forthcoming. The 

 latest account from the Utah mines is that the substance in 

 question is cadmium, which, although valuable, is perhaps 

 less so than tin, in view of the threatened exhaustion of the 

 best-known mines. It is now reported that some rich depos- 

 its have been found in the Department of Lozere, in France. 

 15 A, November 11, 1871, 629. 



CAUSE OF SMOKINESS IN QUARTZ CRYSTALS. 



Mineralogists are well aware that in 1868 a large number 

 of crystals of smoky quartz were found in Switzerland, which 

 furnished specimens of great beauty and size to many cabi- 

 nets throughout the world. In the course of an investiga- 

 tion into the physical characters of some of these crystals, it 

 was found, much to the surprise of the experimenter, that on 

 heating they lost their smoky appearance, and became as 



