. Bulletin of the Department of Geology. Geology. 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
. Bulletin of the Department of Geology. Geology. 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. Velardena, Mexico.—The Velardena district is an area of folded Cretaceous ( "?) limestone overlain by andesitic tnft's and flows and traversed by andesitic 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. Please note that these images are extracted from scanned page imag
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