424 Reviews — Tables for the Determination of Minerals. 



form is chosen as an index ", may to a certain extent be conceded ; 

 but it must always be remembered that zones are not based on the 

 fauna of a lithological division or formation ; they are established by 

 careful collecting of fossils stage by stage, and the zonal subdivisions 

 ultimately adopted may or may not correspond with the lithological 

 or purely stratigraphic divisions. As Dr. Rowe remarked in reference 

 to Chalk zones, he " pins his faith to Zoology, and to Zoology alone", 

 while at the same time he called attention to instances where the 

 lithological and zoological boundaries happened to coincide. We are 

 glad to see the term Bathonian restricted to the Great Oolite Series. 



VIII. — Tables foe the Determination of Minerals by means of 

 their Physical Properties, Occurrences, and Associates. By 

 Edward Henry Kraus, Ph.D., and Walter Fred Hunt, A.M. 

 8vo ; pp. 254. New York and London : McGraw-Hill Book 

 Company, 1911. Price $2 (8s. 6d.) net, post paid. 



rPHIS set of tables is framed for the ready determination of 250 

 J_ mineral species, on the basis of easily recognizable physical 

 properties. Lustre and colour are the chief fundamenta divisionis ; 

 streak, hardness, and specific gravity being among the other characters 

 tabulated. The tables are in two parts, according as the lustre is 

 metallic or non-metallic ; and colour is made an important basis, 

 although for purposes of classification it is far from definite, and in 

 the present work leads to much repetition. 



The Introduction comprises a brief sketch of the physical properties 

 of minerals, sufficient, possibly, to enable persons with a small 

 amount of technical knowledge to handle the book with advantage. 

 A glossary follows, and although this is delightfully brief and on the 

 whole adequate, it might be improved by the excision of some terms 

 and more attention to the connotation of others. The word ' waxy ', 

 for example, is given in the column describing lustre, and on referring 

 to the glossary we learn that 'waxy' means " luster of wax". 

 ' Interlaced,' we are told, means " intertwined, confused " ; while 

 'refraction, double' is defined as "yielding two refracted rays", 

 a definition that might well be objected to as logically inadequate. 



Three kinds of type are used for the names of various species, and 

 this feature is designed to indicate their comparative importance, and 

 also to enable the book to be used by students of different grades. In 

 this connexion it might be noted that the rarer felspar anorthite 

 is given more prominence than labradorite. The authors have paid 

 special attention to the associates and modes of occurrence of the 

 minerals with which they deal, and valuable observations are to be 

 found in the column relating to these features ; but in the case of 

 cassiterite there is no mention of chlorite as one of its important 

 accompaniments. 



The information is arranged as conveniently as possible, and 

 opposite each name references are given to the well-known manuals 

 of Kraus, Dana, and Moses & Parsons. The book is singularly free 

 from typographical errors, though the spelling of ' sanidine ' (p. 238) 

 seems to have escaped revision. These tables evidence great care as 



