-Metallos'ény of tho Japaneso Islands. 



2. Classification of Ore-deposits. 



vox Waldensteix^^ and vox Cotta'^ were the first geologists 

 to try (in 1824 and in 1859) to classify ore-deposits. Since then, 

 many methods of classification liave been proposed from time to 

 time. Groddeck's system, "^^ which takes as the basis of classifica- 

 tion the origin of the deposits, is perhaps the best of all. He 

 divided ore-deposits into two groups, viz., original and fragment- 

 ::ary deposits. 



Van Hise*^ a little later classified them into three groups, 

 namely, those of igneous origin, those which are the direct result 

 •of sedimentation, and those which have been deposited by under- 

 ground water. A classification based on the magmatic theory is 

 perhaps the best for us, when looked at from the standpoint of 

 the theory. Tlie greater part of the ore-deposits in the case of 

 the heavy metals is of igneous origin, and also since there are, 

 in my opinion, hardly any other deposits of heavy metals found in 

 •Japan. Accordingly I shall here classify them into five categories, 

 based on the magmatic theory: 



a) INIagmatic segregations. 



b) Contact deposits. 



c) Mineral veins. 



d) Replacement deposits. 



e) Impregnation deposits. 



This classification has been made quite independently by me 

 for the special treatment of Japanese ore-deposits. I am, however, 

 ver}^ glad to notice its close resemblance to that of Richard Beck, 

 made public in the third edition of his ' ' Lehre von den Erz- 

 lagerstaetten," 1909. 



Magmatic segregations are heavy metals accumulated in a 

 magmatic body. Contact deposits are the so-called fossil ema- 



1) von Waidenstein : " Die besonderen Lagerstätten der nutzbaren Mineralien," 1S24. 



2) von Cotta : "' Lehre von den Erzlagerstätten," 1859. 



3) von Groddeck :" Die Lehre von den Lagerstätten der Erze " 1869. 



4) Van Hise : " The Genesis of Orj Deposits," pp. 2S2-432. 



5) Lincoln : Loc. cit. 



