342 The Philippine Journal of Science 1915 



The material from each 3 meters of drill hole constitutes a 

 separate sample. Occasional samples were taken from the sur- 

 face, also. The analyses tabulated are on samples selected as 

 representative of a total of 183 samples, taken from 89 different 

 drill holes. The drill holes were located at regular intervals, 

 usually at the corners of 300-meter squares, and groups of drill 

 holes were distributed over different parts of the ore deposit. 



From the foregoing analyses it appears that the average ore 

 from Surigao would contain 52.5 per cent of iron after being 

 sintered or nodulized in preparation for smelting. If two con- 

 spicuously poor samples, both of which probably are contami- 

 nated with the underlying parent rock, be excluded, the average 

 iron content of the sintered ore becomes 53.9 per cent. Even this 

 figure is somewhat lower than the average iron content of the 

 ore mined at Mayari, Cuba, by the Spanish-American Iron 

 Company. The yearly output of this company averages 48 to 

 49 per cent iron in the dry ore and 55 to 56 per cent iron in 

 the nodulized ore.^ Another important difference between the 

 Cuban ore and the ore from Surigao Province is in their re- 

 spective nickel contents. The average Cuban ore carries about 

 1 per cent of nickel, while no nickel has been detected in the 

 Surigao ore. 



The observation has been made in the Cuban deposits that 

 the iron content of the ore increases for a certain distance below 

 the surface and then declines. The samples from Surigao show 

 a similar change generally, but not in all cases; some holes 

 reveal a progressive decrease from the surface downward. It 

 is notable that the very shallow holes encountered relatively poor 

 ore, while the deepest holes show the best ore. This may be 

 due in part, however, to a tendency to drive the shallow holes 

 farther into the t)arent rock, proportionally, than in the cases 

 of the deeper holes. 



QUANTITY OF ORE 



The quantity of ore is estimated upon a basis of the total 

 area of the iron-ore deposit as determined by our reconnaissance 

 surveys and the average depth of the ore as determined by drill- 

 ing. The Coast and Geodetic Survey base map upon which our 

 surveys are plotted is accurate, but the position of the line 

 which marks the interior limit of the deposit is determined only 

 approximately. The figure for the average depth of the ore is 



" Kemp, James F., loc. cit., 131. 



