IX, A, 3 Dalburg and Pratt: Iron Ores of Bulacan 205 



The ores which are mined at present average more than 60 

 per cent of metaUic iron, but the bulk of the ore reserves is 

 probably somewhat lower in iron. Phosphorus is below the 

 Bessemer limit in most of the ores. Sulphur is not generally 

 present in prohibitive amount. Siliceous ores, which are not 

 utilized at present, occur in considerable proportion. 



The origin of the ores is ascribed to contact phenomena at- 

 tendant upon the intrusion of the dike rocks, although the re- 

 placement ores are not confined to immediate contacts and there 

 is little evidence of extreme high-temperature mineralization. 

 The findings do not support the theory which had been suggested 

 previously that the ores are surficial deposits resulting from the 

 alteration of pyrite and other iron-bearing minerals and the 

 concentration of the resulting iron by surface waters; conse- 

 quently, the economically important conclusions based on this 

 theory that the ore will become more pyritiferous with depth 

 and will fail entirely within a short distance from the surface 

 do not apply. On the other hand, it is reasonable to assume 

 that the ore will persist unchanged to a depth commensurate 

 with the other dimensions of the outcrops. 



Although an unqualified statement of tonnage cannot be made 

 with development at its present stage, it is reasonably certain 

 that more than one million tons of ore are available. The 

 correctness of this estimate could be ascertained by simple ex- 

 ploration work at no great cost. It is probable that several 

 times this quantity of ore is available. 



The ores are at present exploited in a small way by Filipinos 

 who produce cast-iron implements, such as plowshares and plow- 

 points, directly from the ore by a primitive smelting process. 

 The beginnings of the smelting industry date back as far as 

 1664, and although the process has borrowed methods from both 

 the Spanish and the Chinese it is unique in many respects. Like 

 most primitive smelting operations, the process is not efficient 

 although it is profitable under existing conditions. The ores 

 are not self fluxing as has been stated, but as the process is con- 

 ducted a suitable slag is automatically formed from parts of the 

 furnace walls. Quartzose ores which are at present discarded 

 ought to be utilized, and a plan by which they could be utilized 

 is suggested. 



The Bulacan ores might be exploited on a larger scale by the 

 electric smelting of iron and steel. The fundamental require- 

 ments, such as suitable ore, water for hydroelectric power, char- 

 coal, and fluxes for reduction, etc., are met in the conditions 



