272 Reviews — Phillips' Mineralogy. 



to rocks in general, and would better have formed part of a general 

 introduction to the whole work, if there is in truth to be a volume 

 on the igneous rocks. The authors might have availed themselves 

 of the space left free to discuss the classification of the sedimentary 

 rocks. 



Mr. Crook, of the Technological Department of the Imperial 

 Institute, contributes an extremely valuable appendix on the 

 systematic examination of loose detrital sediments. He has had some 

 years of experience of the investigation of such material, and the 

 hints that he is able to give will he welcomed by those with less 

 experience and skill who maybe faced with a similar task. Mr. Crook 

 is a strong advocate of magnetic separation. An ordinary horseshoe 

 magnet has, of course, long found a place in mineralogical laboratories 

 for separating purposes in the analyses of rocks and meteorites, but 

 by the use of an electromagnet he has elaborated a ready and useful 

 method, which in conjunction with heavy liquids very speedily 

 resolves detritus into its component mineral parts. The ordinary 

 optical methods are referred to, and the general characters of the 

 detrital minerals are summarized. 



A good index brings the book to a close. 



VIII. — Mineralogy. By A. H. Phillips, pp. x + 699, with 

 534 figures in the text. 2Ne\v York : The Macmillan Company, 

 1912. Price 16s. net. 



REASONABLE in price and size, and well illustrated, the text- 

 book on mineralogy written by Dr. Phillips, the professor of 

 mineralogy at Princeton University, may safely be commended 

 to the use of students who, while not wishing to specialize in 

 crystallography or mineralogy, desire to acquire sufficient working 

 knowledge of these subjects to enable them to determine the minerals, 

 whether megascopic or microscopic, constituting the rocks which they 

 may happen to be investigating. The author has successfully con- 

 trived to avoid unnecessary abstruseness without sacrificing lucidity 

 or slurring over difficulties. 



The book is divided into three parts, viz. Crystallography, 

 Descriptive Mineralogy, and Determinative Mineralogy, of which 

 the second is about as long as the other two together. The author 

 considers at some length the morphological characters of crystals, 

 and makes use of Miers' nomenclature for the classes of crystalline 

 symmetry. Twinning and parallel growths are amply treated in the 

 chapter on the relation of individual crystals. The measurement of 

 crystals and the use of the goniometer are somewhat perfunctorily 

 dealt with, but the optical properties are fully and clearly discussed. 

 Chapters on the other physical characters, such as cleavage and 

 fracture, specific gravity and its determination, structure, colour, 

 streak, lustre, phosphorescence, and fluorescence, and on the relation 

 of minerals to the elements, and the origin of minerals are included 

 in the next part. The description of the principal mineral species, 

 which takes up the bulk of the second part, is well arranged. Under 

 each species are given its chemical and physical properties, the nature 



