30 Mineralizers in Ore Segregations [228 



deposits are simple basic rocks abnormal in containing much 

 pyrrhotite, chaicopyrite and pentlandite," and, " Some de- 

 posits in which the ore consists mainly of solid pyritic 

 minerals present features which can hardly be explained 

 otherwise .than by actual injection of molten sulphides," in 

 spite of his admission that " on the whole the sulphides are 

 the latest products crystallized." In reply to the advocates 

 of a hydrothermal origin for certain of these deposits, % he 

 charges them with having confused secondary changes with 

 primary deposition. 



DeLaunay's treatment of these deposits differs consider- 

 ably from any of the preceding. The first five divisions of 

 his genetic classification of ore deposits are the following: 



1. Gites d'Inclusions. 



2. Gites de Segregation. 



3. Gites de Depart Immediat ou de Segregation Peri- 



pherique Sulfuree. 



4. Gites de Contact du Type Banat. 



5. Impregnations Diffuses de Profundeur (includes amas 



pyriteux) . 



" Deposits of inclusions are those where a useful mineral 

 occurs in an igneous rock in the same relation as the other 

 constituent elements." This division is of theoretic rather 

 than practical importance, and includes only native metals 

 and oxides present as normal accessory constituents of an 

 igneous rock without the intervention of mineralizers. The 

 segregation deposits, he says, might be regarded as having 

 been effected without intervention of volatile constituents, 

 nevertheless the general opinion today is that water and pro- 

 bably other mineralizers have played a role, though he con- 

 siders them formed in a medium poor in mineralizers. The 

 ores are native metals and oxides. The Gites de Depart 

 Immediat, or peripheral sulphide seregations, he says, have 

 usually been considered examples of true segregations which 

 differ from the internal oxidic segregations by their position 

 and nature. DeLaunay believes it necessary, however, to 



