1916] Umpleby: Ore on the Limestone Side of Garnet Zones 29 



the development of the garnet-epidote mass at the Peacock Mine, a 

 suggestion confirmed by the occurrence of marble in diamond-drill 

 cores which come from the deposit, although the location and direction 

 of the hole is not known to the writer. The point of particular interest 

 is that the ore-body occurs in the central part of the garnet mass. 



The Seven Devils deposits exhibit both exomorphism and endo- 

 morphism, the latter being clearly shown by the stringers and replace- 

 ment bodies of epidote in the diorite several feet from limestone 

 contacts. 



Velarde na, Mexico. — The Velardena district is an area of folded 

 Cretaceous ( "?) limestone overlain by andesitic tnft's and flows and 

 traversed by andesitic dikes. The principal intrusive rocks are dikes 



SCALE Of FEET 



t 5 3a 



Fig. 1. Transverse section showing relations of ore to limestone and quartz- 

 diorite in Intermediate Stope, Queen No. 1 Mine, Seven Devils, Idaho. 



and necks of alaskite and traehytic alaskite accompanied or closely 

 followed by extensive injections of dioritic rocks. All of the intrusive 

 rocks have caused metamorphism and at a time "definitely subsequent 

 to intrusion, ' ' as shown by extensive endomorphism. The ore deposits 

 are of varied character and clearly indicate successive stages of depo- 

 sition. "Sulphides began to be deposited with the lime-silicates, but 

 the chief sulphide deposition followed the lime-silicate period directly, 

 with quartz as principal gangue. " 10 



The Copper Queen is the principal copper ore-body of the district 

 and consists of three main pipes in metamorphic rock at the contact 

 of the diorite intrusion. The principal sulphides are cupriferous 



11 Spurr, J. E., and Garrey, G. H., Ore-deposits of the Velardena District, 

 Mexico, Econ. Geol., vol. 3, pp. 688-725, 1908. 

 io Op. ext., p. 724. 



