REVIEIVS 717 



Branner, J. C, AND Newsom, J. F. The Phosphate Rocks of Arka7isas. 

 Bull. 74, Arkansas Agric. Exp. Station. 8vo, 67 pp. 



Three phosphate-bearing areas are noted in Arkansas. The first, and by far the 

 most important, lies north of the Boston Mountains and west of Black River; the 

 second, in the Cretaceous area of the southwestern part of the state ; the third, north 

 and west of Hot Springs. The second and third areas may be dismissed with the 

 remark that little appears to be known concerning the phosphate beds they may contain- 



The principal area is that in the northern part of the state. The phosphates here 

 •occur as nodules associated with the Sylamore sandstone and Eureka shale. These 

 two formations together have a maximum thickness of 90 feet, and represent the 

 Devonian of the region. The phosphates are therefore at the same horizon as the 

 Tennessee black phosphates. Average specimens gave a phosphoric acid content 

 ■equivalent to 30 per cent, to 70 per cent, calcium phosphate, with 4 per cent, to 20 per 

 <;ent. iron and alumina. Unless better material is found, the rock will evidently be 

 unable to compete, except locally, with Tennessee or other southern phosphates. 



Crosby, W. O. "Geological History of the Hematite Iron Ores of the Ant- 

 werp and Fowler Belt in New York." American Geologist, Vol. XXIX, 

 pp. 233-42; also in Technology Quarterly, Vol. XIV, pp. 162-70. 

 The author discusses certain of the red hematite deposits of the western Adiron- 

 dacks and concludes that the "ore body of the Sterling mine is in a dike, 50 feet or 

 more in width, of some highly altered basic rock, possibly diabase ; that the ore was 

 originally a magmatic segregation of this rock, chiefly in the form of sulphides, which 

 have subsequently suffered more or less complete oxidation to a considerable depth, 

 the ore now being virtually a gossan; and that this dike is, probably, continuous for 

 the entire length of the belt of mines, although absolute continuity is by no means 

 •essential to the hypothesis." 



[It will be remembered that the "dike" in which the ore bodies occur is bordered 

 by- granite on the southeast, and by crystalline limestone on the northwest; and that 

 Smyth has considered the chloritic " dike " rock to be merely a highly altered phase 

 •of the granite.] 



Dickson, C. W. "The Ore Deposits of Sudbury, Ontario." Trans. Am. 

 Inst. Min. Eng., Vol. XXXII ; advance separate, 65 pp. 

 The first part of this paper deals with "The Relation of Nickel to Pyrrhotite." 

 The mineral associates, chemical composition, and nickel and cobalt content of 

 pyrrhotites are discussed, particular attention being paid to the Sudbury and Algoma 

 •ores. The author states that "the nickel occurs in the pyrrhotite as the so-called 

 pentlandite," but that, though "nearly all of the pentlandite can be separated from 

 the pyrrotite by magnetic methods," "peculiar physical conditions seem to render 

 its absolute elimination an impossibility." Magnetic separation is therefore a 

 •commercial impossibility. The further conclusion is reached that the Sudbury 

 pyrrhotite conforms best to the formula FegSg. 



The second part is entitled " Genesis of the Sudbury Ores," but contains in 

 :addition much material bearing on other districts. The Sudbury deposits and ores 

 are discussed in detail, and the author concludes that the origin of the deposits is to 

 •be referred to replacement of the basic rock along crushed and faulted zones, and 

 not to magmatic segregation. This conclusion is based upon the following line of 

 argument : 



Brecciation, with accompanying faulting and shearing, is noticeable both on a 



