Revieics — J. Malcolm Maclaren — Gold. 227 



with the general relations of auriferous deposits. After a brief 

 introductorj- chapter upon the processes which have led to ore- 

 deposits, the author proceeds to describe carefully and fully the 

 crystalline characters of gold and its native alloys and compounds. 

 The text is accompanied by numerous excellent drawings of typical 

 crystals, and good illustrations of various well-crystallized nuggets 

 are given on plates, the frontispiece being a coloured picture, natural 

 size, of the fine nugget — the " Latrobe " — which is treasured in the 

 British Museum collection. The statement on p. 29 regarding the 

 telluride of gold, calaverite, that "such crystallized specimens as 

 have been found have been too imperfect to admit of the determination 

 of the crj'stallographic system ", was probably penned prior to the 

 discovery some ten years ago of numerous brilliant many-faced 

 crystals at Cripple Creek. The precise system is, indeed, still in doubt 

 on account of the extraordinary complexity of the crystallization. 

 The number of forms that have been observed on the rare mineral 

 krennerite is considerably larger than that given on p. 33. The 

 next chapter is concerned with the classification of auriferous deposits. 

 Dr. Maclaren dismisses all systems which are based upon considerations 

 of the form of the deposits and the nature of the association as 

 useless from either a scientific or an economic point of view. Gold 

 has often been found in the last place that might have been expected 

 from the theoretical considerations put forward by various writers. 

 Upon this still debatable point the author is not dogmatic, but thinks 

 that the gold-bearing regions may conveniently, if empirically, be 

 grouped according to a combination of geographical and geological 

 data as follows : primary, {a) connected with the extrusion of inter- 

 mediate or basic igneous rocks (andesites or diabases), {b) connected 

 with the extrusion of acid rocks of granodioritic type ; secondary, 

 (a) deposits produced or modified by chemical agencies, {b) deposits 

 produced by mechanical agencies. The primary group is defined to 

 include gold which has had apparently "no prior state of combination 

 and no former locus in space " ; the metal in the secondary group is 

 " obviouslj' or presumably derived from sulphide or telluride ores, or 

 from gold-quartz ". Such a classification clearly cannot be considered 

 very hard and fast, but pending further research it serves the purpose. 

 Typical examples of the various sub-groups m different parts of the 

 world are briefly described. Many important questions are discussed 

 in this chapter, such as the formation of nuggets, about which there 

 has been so much controversy, and the deposition and concentration 

 of gold. 



The second part, which occupies nearly three-quarters of the book, 

 comprises full descriptions with great wealth of detail of all the known 

 occurrences, arranged geographically — Europe, Asia, Australasia, 

 Africa, America — and furnishing most fascinating reading. So far as 

 possible, the author gives for each district the history of the mines, 

 the geological features, the methods of working, and statistics of the 

 output. The text is accompanied by many admirable illustrations, 

 both plans and reproductions of photographs of various districts. 

 Adequate discussion of this part is beyond the limits of a review ; we 

 can but commend the readincr of it. 



