36 abstracts: chemistry 



INORGANIC CHEMISTRY.— The role of hydrolysis in geological 

 chemistry. Rogers C. Wells. Economic Geology, 6: 211-217. 

 1911. 

 Owing to hydrolysis most solutions that are active in geologic changes 

 are either alkaline or acid, rarely neutral. The nature of the hydrolytic 

 reaction for several salts is described and it is shown that geologic action 

 may often be proportional to the concentration of hydroxyl ion in a 

 solution even though, as with carbonates, it is a "salt" which is assumed 

 to be present. Owing to the increasing ionization of water at high tem- 

 peratures, as well as the increasing hydrolysis of salts, hydrolysis becomes 

 extremely marked at such temperatures. This may help to explain 

 the action of water as a "mineralizer." R. C. W. 



MINERALOGY. — The relation of bomite and chalcocite in the copper 

 ores of the Virgilina District of North Carolina and Virginia. Fran- 

 cis Baker Laney, Geological Survey. Proceedings of the United 

 States National Museum, No. 1835, 40: 513-524, Pis. 63-69. 1911. 



The rocks of the Virgilina District are greenstone and sericitic schists 

 cut by granite and gabbro. The intrusive rocks show no schistosity. 

 The schists have been derived from volcano-sedimentary rocks of two 

 types — andesite and quartz porphyry, with tuffs corresponding to these 

 rock types. Their age is probably early Paleozoic. 



The veins have a more northerly trend than the schistosity of the 

 country rock. Their filling is quartz with local and varying amounts 

 of epidote and calcite. The ore-bearing veins are confined to the more 

 basic portions of the greenstone schists, and the ore lies in well-defined 

 shoots. 



The ore minerals are bornite and chalcocite. They are chiefly in 

 quartz, but are not confined to any one of the gangue minerals. Bornite 

 is in slight excess over chalcocite and is apparently of only one period of 

 deposition. Chalcocite is of two periods — one confined to the upper 

 portions of the vein, younger than, and filling a network of minute 

 fractures in, the bornite; the other contemporaneous and intergrown 

 often crystallographically with it. There is no evidence that any of 

 the bornite is secondary. It is, therefore, clear that in the Virgilina 

 District the greater part of the chalcocite is a primary mineral contem- 

 poraneous with the bornite. F. B. L. 



