proceedings: geological society 231 



The Quisque deposit, 80 miles northwest, was discovered in 1905. 

 Vanadium is found as the sulphide, patronite, which is one of three sub- 

 stances forming a dike-like mass which fills a fault-fissure in Cretaceous 

 shales. The deposit is in the center of an area in which igneous activity 

 has been intense. The three substances composing the dike, are pat- 

 ronite, a sulphide of Vanadium; quisqueite, a highly sulphuretted bitu- 

 men; and a substance composed almost wholly of carbon. Analyses 

 of the substances as well as microphotographs were shown which indi- 

 cate their origin. The dike appears to have been forced into the fault 

 fissure when molten : quisqueite and carbon segregated successively and 

 patronite forms the eutectic of the mass. 



By oxidation of the sulphide of vanadium a heavy gossan of oxidized 

 minerals was formed, in which three new vanadates were found. The 

 deposit is actively exploited and is the source of most of the vanadium 

 of the market at present. 



Remarks on the geology of the Panama Canal Zone. D. F. McDonald 

 and T. Wayland Vaughan. 



The 251st meeting was held in the Cosmos Club January 24, 1912. 



New dolomite formations in Alabama. Charles Butts. In a recent 

 survey of the Birmingham district, Ala., three new dolomite formations 

 have been recognized, which were included in the reports of the Alabama 

 Geological Survey in the lower part of the Knox dolomite. These are 

 named, in descending order, the Potosi, Ketona, and Brierfield dolomites. 

 The Brierfield is a steely-gray, highly siliceous formation 1200 feet thick. 

 Some samples carry 40 per cent silica. The silica is mostly disseminated 

 in the forms of quartz, filling small cracks and replacing the dolomite. 

 On weathering the silica forms on the dolomite a crust which is either 

 cavernous or covered on the outside with an irregular network of narrow 

 ridges, giving a highly characteristic appearance, by which the forma- 

 tion can be recognized easily and certainly. The name is from Brier- 

 field, Ala. The Ketona is a light-gray, coarse-grained, and very pure dolo- 

 mite, running generally less than 2 per cent of insoluble matter. It is 

 275 to 800 feet thick. This rock is used for flux almost exclusively by 

 the smelting furnaces of the district. The name is from Ketona, a quarry 

 town several miles north of Birmingham. The Potosi is almost identical 

 in character with the Brierfield and 275 to 500 feet thick. It is corre- 

 lated with the Potosi dolomite of Missouri, whence the name. The 

 Potosi and Brierfield dolomites are known only in the southwest corner 

 of the Bessemer quadrangle, while the Ketona extends throughout the 

 Bessemer and Birmingham quadrangles. 



The Brierfield dolomite overlies the Conasauga limestone, the top of 

 which is correlated with the top of the Nolichucky shale in Tennessee, 

 where the Nolichucky is immediately overlain by the typical Knox dolo- 

 mite. In Alabama, however, where the three new dolomites described 

 above occur, the Potosi dolomite is overlain by the Knox dolomite, which 

 is the equivalent of the Knox of Tennessee. Therefore in the Tennessee 

 section there is a hiatus between the Knox dolomite and the Nolichucky 

 shale which in Alabama is filled in part by the 2500 feet more or less of 

 dolomite described above. 



