Arizona republican., 1909-07-11

capacity of at least 800 tons day:
 later on even still larger plant of
 thousand tons capacity or more
 will be constructed
 Edward w. Brooks, the consulting
 engineer for the London Arizona Cop
 per company and other Tinney prop
 critics, has recently made an exami-
 nation of the Fl Tiro in order to
 study the geology. structural condi-
 tions and ore occurrences there.
 As consulting engineer for the Ari-
 zona Smelling company, Mir. Brooks
 was commissioned, in 1906, to make a
 detailed study of the geological con-
 ditions, ore deposits and the possibil-
 ity of successful mining operations
 throughout the Arizona Copper Belt.
 A favorable report made upon the
 Bill Williams country which called the attention of Arizona to the great possibilities of the region, has result the Colorado river and great activity throughout the district
 The two years spent In working out the geology and ore occurrences in the London Kelvin district resulted in the organization of the companies which have recently developed some of the greatest copper deposits in the United States
 The geology of Fl Tiro is analog- ous to the contact metamOrphic de- posits of Arizona and the Sonora province, exhibiting the same general fOrmatiOnal features common to near ly all; a basal complex of Cam brian schists originally supported a series of sedimentary beds, ranging from the Cambrian to probably Gre taceous times The Carboniferous period was represented by many strata of limestones and shades, while the deeper beds of the Cambrian rep resented by the quartzites and com glomerates, with intervening beds of Devonian limestone and shale Fro sion later stripped away the sedi- mentaries in the region of the Fl Tiro, exposing a series of intrusive rocks over a large area with only fragmentary masses of the sedimen- tary beds left. Following the laying down of these sedimentaries, an in trusion of granite broke through and lifted the strata into a dome shaped mass forming a great laccOlith be- tween them and the underlying schists. This has been named locally the Imperial Granite" It is d coarsely crystalline rock and forms the surface over a large area in this locality. Later dioritic porphyry in- truded this granite in the form of dikes, forming with the other intru- e.iA ed by the development of epidOte. garnet and other typical minerals in the blocks of limestone remaining. The foregoing eruptive periods were not accompanied by any copper min- eraliZation. Subsequent to the above intrusions, occurred an- other intrusion of porphyry named the Fl Tiro porphyry. which is prob able a monzonite. This closed the acidic, silicious intrusive period and the more recent basic intrusive had no influence on the ore deposition.
 The Fl Tiro porphyry intrusion crushed, shattered and ground to- gether the enclosing rocks, as a re- suit of which the granite was frac- tured and sheeted developing as well. a system of cross joints of minor inn portaHce, all affording channels for the circulating mineralizing waters. There was also a chemical activity set up, the vapors and gases attacking the surrounding rocks, changing some of the minerals and removing entirely others. Following this pneumatolytic period the cooling porphyry sent out waters carrying silica into the adia- cent granite often three hundred feet distant. These different agencies caused a circulation of chemically ac- tive waters partly of magmatic origin and part surface waters With very little doubt the Fl Tiro porphyry was the original mineraliZing magma. The waters undoubtedly leach ed this porphyry of it's original cop per minerals and in circulating through the granite, deposited their oad and concentrated it, making the I copper deposits.
 These localities later enriched by ocalized migration constitute the principal ore bodies in the property md are found in the granite, as noted ibove and along the contact of the granite with the Fl Tiro porphyry.
 I Htit iS Ol lluiAihS anu in the property, but he greater part occurred prior to the )re deposition. so that any sudden :utting off of the ore bodies is not o be expected.
 That part of MT Brooks report of he greatest economical importance, 
 "The size of the ore bodies is mo- where determined in the present work ut they are evidently very extensive | IS ifs to be expected in occurrences of he nature of those in the Fl Tiro. l They constitute a border one around | he margin of the Fl Tiro porphyry | mass, and may be expected to have | | width of from one to three hundred eet or more closely corresponding to he areas of contact metamorphism as teen in the imperial granite at the Iurface. They will propably extend to depth of many hundreds of feet. | There exists no data upon which any 1 'eliable estimate of the ore reserves n the Fl Tiro mine can be safely | based. That they will be ample to l sustain extensive operations for many