440 : ■ : SMITH ANI)-:^DDINGFIELD, v. 



the "Military -Gut-off" Road near Government Center. Samples from 

 this location were assayed by Mr. Durrell, formerly superintendent of 

 tlie Headquarters Mining Company, and found to cai-ry from 1.80 

 pesos to 2.80 pesos in gold per ton. Mr. Hulbert of the Major Mining 

 Co. reports "colors" from pannings of matenal in a small quartz and 

 calcite lead about 20 meters from the hot spring at Itogon. This spring 

 is located on the strike of this vein. 



We find three distinct modes of the occurrence of gald. In the 

 Gold Creek-Batwaan system the metal is present in quartz veins with 

 small amounts of cinnabar, tellurium, galena, several copper minerals, 

 chromite and others, but with practically no manganese. In the upper 

 part of Antamok we find gold quartz veins \\-ith a subordinate amount of 

 calcite but a large amount of manganese oxide. In the lower parts of 

 Antamok Creek the gold occurs in calcite veins with heavy oxide. The 

 manganese is also encountered in the form of the carbonate, rhodo- 

 chrosite. ' - 



Such differences are due to a variation in the rocks through which 

 the underground water traveled and the minerals which it dissolved 

 before it reached the trunk channels and precipitated its solute. The 

 following facts seem to give fairly conclusive evidence that the gold 

 was deposited in general from ascending waters: (1) The relation of 

 the deposited gold to recent spring deposits was shown above; (2) 

 the presence of richer values of primary ore beneath and close to the 

 hanging wall in some veins. 



The veins in this district are similar in many respects to those of 

 California and parts of Australia. PjTite is the dominant sulphide 

 in the ore. The . gold solution at first probably decomposed the pyrite 

 and produced a salt of iron which in turn precipitated the gold. Ferrous 

 sulphate formed by oxidizing waters acting on pyrite, as well as com- 

 pounds of tellurium, are known to be precipitants of gold. 



The occurrence of manganese in gold veins has been shown to be 

 of great importance in other parts of the world. Recently, Emmons 

 has published two rather complete expositions of the subject,'^ setting 

 forth the results of both laboratory and field work. Ferguson of tlie 

 Bureau of Science, in an article on the Geology and Mineral Resources 

 of the Aroroy District, Masbate,* has shown the application of these 

 results to that field. The following is a quotation from Emmons' Paper : 



Ferric iron, cupric copper, and manganitic manganese are present in ma?ry 

 mineral waters, and under certain conditions any one of them will liberate clilovine 

 from sodium chloride in acid solutions. Nascent clilorine dissolves gold. Each 

 of these compounds releases chlorine at high temperatures, or in concentratfe^ 

 solutions. In cold, dilute, acid chloride solutions, ferric iron will not give nascent 

 chlorine in appreciable quantity in 34 days, and cupric copper is probably even 



' Am. Inst, Mm. Eng. Bull, (1910). 768; Journ.. Gepl. Chicago ( 191,1.,).. ^^19, ^V>., 

 ' ^ This Journal, Sec. A (1911), 6, 3^i. ' -.m.. •■.-■ 



