REVIEWS 821 



shales. The absence of the S0 4 radicle does not dismiss the possibility 

 of connate waters as a source of the mineral salts. The sulphates 

 originally in the connate waters may have been lost as the waters moved 

 along toward the surface by some such chemical reaction as the precipita- 

 tion of gypsum by the action of sodium sulphate on calcium carbonate 

 in the presence of free C0 2 . 



Thus the chief problem that this quadrangle offers is held in question 

 still, but this is not due to lack of skill or painstaking effort on the part 

 of the authors of this report. It is a worthy contribution to the geologi- 

 cal literature of this state. W. B. W. 



Genesis of Pyrite Ores of St. Lawrence County. By C. H. Smith, Jr. 

 New York State Museum, Bull. No. 158, 191 2, pp. 143-82. 

 Figs. 29. 



Under the most favorable conditions, definite conclusions regarding 

 the geneses of ore bodies cannot always be drawn, and when these are 

 found in bodies of rock as highly metamorphosed as the Grenville series 

 many complications arise. 



In this area, pyrite is widely disseminated, but the ore bodies are 

 associated only with "rusty gneisses thought to be metamorphosed 

 impure sandstones and shales." The writer believes that the metallizing 

 period was subsequent largely to the main period of metamorphism, and 

 was brought about by magmatic emanations permeating the gneisses 

 and replacing with pyrite certain minerals which are usually very stable. 

 These emenations came from the abundant intrusions after active move- 

 ment of the magmas had ceased. It is not stated that the pyrite all 

 came from the magmas. In fact, to explain the association of the ore 

 bodies with the gneisses alone, it is suggested that only the sulphur 

 was of igneous origin, and that the iron was furnished by the meta- 

 morphosed sediments. To cover minor occurrences of pyrite three addi- 

 tional periods of formation are postulated, but are not considered to have 

 been of importance in determining the ore bodies. 



Additional points of interest are found in the lack of association of 

 the ore bodies with gabbros, as some authors have stated in other areas, 

 and possible genetic relations of pyrite with associated graphite. 



The explanation of the ore bodies strikes one as quite involved, but 



the author assures us that it is in very small proportion to the complexity 



of field problems and conditions. 



W. B. W. 



