The Alaska daily empire., 1915-12-29
MINING PAPER
 DEFENDS BRADLEY
(san Franciaco Mining and Scientific
 prces

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 Our esteemed contemporary on Manhattan island. (Aiinins and Engi neerlns journaO. iu its interesting ls- sue Of the iih inst. "geta off on the wrong iooi when it states lhat hr F. w. Bradley and hla associates op- leratlns the Troadwell group wore skopilcal oi the claims made by the Jacillng group in regard to what could bo done in low-grado goid-mlnlng on thc Persoverance.GaGtlue8u lode and Of ihe development of Che Alaska. Ju. noou as undertaken by themselves un- tn they became converted" by the results obtained by their neighbors The question is not one merely of ! priority. it goes to Che heart Of the en- tire problem Our readers ought to be well aware oi the iacts for they were stated clearly In our issue of December 6. 1913. However we have added so many new subscribers since that date that it Is worth while to re-state the orig.n o fthe Juneau en- terprise After an enormous lode of low grade ore in slate has been proved by the shallow workings Of ihe Ju- neau starting from surface ln Silver Bow Basin. it was planned as early as 1899 to tap the lode by @ lcw-lovel adit This work was begun ia 1909. but financial arrangements assuring the completion or it were not nude until August 19l0 when Mr. Bradley entered into @ contract with the Ai. laska-Juneau company to drive the ad- it for a share-interest In 1912 MT. D. C. Jackiing appeared on the scene. and looked into Che prospects ci ihe adjoining Perseverance property Un- Idoubtedly be was led to consider the big scheme of development since put Into effect by the Alaska Gold Mines which controls the Alacko-Gas- -ineau property by reason ol the work under taken and plans formulated by the engineers 30 experienced md capable as Messrs F w. Bradley and J. H l Mackenzie 1T Mir. Jackling and his associates were influenced by the in. itiatiye or "the Trocdwell group they were wise. for no amount Of exper. .euce in copper sumcos to solvc the ! problems peculiar Go gold mining. The ] dissemination or chaicocite in mon zonite porphyry exhibits @ degree Of uniformity in strong contrast vith the sporadic distribution Of native gold in quartz veins travcrsing slate In the Juneau Gagtlneau lodc-channel the ore is confined to che quartz lstringers which, by themselves. assay $6 per ton in free gold. The slate ! itraversed by theeo stringors is prac- : tlcaily barren; and SO are the meta. eabbro dikes thot cross the lode. The ! collaborating soludong appear 70 have confined their impregnations to the quartz stringors; they did not enrich the encloeing rock sufficiently to rem der .t valuable lo the miner The de- poslt as g mine. must be interpreted ln terms Of Che gold in these quartz stringers. The original claim Of fl.50 average. made by Che promoters of the Alaska Gold Mines, means min. ing @ width of lode containing % per cent of quartz gtringors This cen be done. but not 4t cost of 70 cents per ton. By careful selection and sorting it ia possible Co send even S6 ore to the mill. but at @ cost entire ly prohibilive. It !s also possible by the indiscrlminate mining of lode mat. ter and quartz stringers Co ensure very low cost per ton. but such min. Ing would reduce Che yield of gold SO as Co render profit out of the Ques. lion. On the other hand. during Che first four years. (1S971s0f) Of opera tions of the Juneau an average yield Of S4.l0 was obtained by sorting 4ik to 1 By selecting the best places and rough sorting in the ratio of l.6 to In the next nine years (1901-1910) an average of S145 was obtained. In g report issued last April. Messrs Bradley and Mackenzie estimate that. after Q given proportion Of sorting. an average ore of about S2 per ton can be obtained and that the selection Of the ore to this degree will prove the most economic. giving 9 profit of 70 cents to Sl per ton on a tonnage Of i500.000 to 100000 per annum. The lode widens in the Juneau to 900 feet. but the ore is largely confined to three widths or bands, which win be mined leaving the intermediate portions to sustain the ground. Whether the dif. ferent treatments Of the problem. breaking Co $125 mill-ore in one case and $2 ore ere modified by dif. ference in the distribution of the ore within the lode is a question yet to be made clear
 In the same article our contempor. ary says that "when 1t is matter Of 50 years llie a gross of less than 6ik per cent is needed to yield 6 per cent net which ls about the basis on which our great mines sell, whether they ought to or not" Evidently the Engi. neerlng and Mining Journal does not know whether 6 per cent is. or is not 2 sufficient yield from Q gold mine. Yet the matter is of some importance to the profession. which Is called upon to advise those that put their money iutol or take it out off, mining prop erty. As WIG h..ve indicated m)re than once, the yield of per cent on a DO years life would be satisfactory f there were any assurance as to the accuracy of that estimate of contin- nous production, but Che fact is that The 5o yearo 50 the roault Of 9 colcu- alton based on several uncertain fac crs' Of which tho most uncertain de- 'ermines the strength or tho whole -hain of casuation. If is moi ,n oer,rr.