IX, A, 3 Dalburg and Pratt: Iron Ores of Bulacan 225 



the stream below the outcrop to the east are numerous very large 

 bowlders of hematite. Across the creek to the north the slope 

 is covered with a talus of disintegrated rock and the ore does 

 not appear. A small vein of quartz and pyrite in the wall rock 

 is exposed a few meters to the east of the ore pit. This vein 

 strikes north 15° east, and pitches 70° to the west. 



The Santa Lutgarda outcrop is at the head of Maarat Creek. 

 The ore appears in the form of a vein some 4 or 5 meters in 

 width. The footwall is fairly well defined, striking north 15° 

 east and pitching west 60°. It is an altered green rock with 

 a fragmental appearance, either tuff or clastic. Massive hema- 

 tite, specularite, magnetite, quartz, pyrite, and occasional small 

 patches of kaolin ( ?) compose the ore. In thin section, Edding- 

 field noted hematite as a primary mineral in quartz. Maarat 

 Creek below the outcrop carries numerous large bowlders of 

 ore. 



Constancia is a veinlike deposit which is poorly exposed and 

 appears to be of lesser extent than Hison or Santa Lutgarda. 

 Comparatively little float ore is found in the creek which flows 

 across the outcrop. The ore is adjacent to the peripheral zone 

 of fragmental granite, but is inclosed in walls of the usual green 

 silicate minerals. The vein displays a width of a meter or more, 

 and the walls carry much ore. The strike is north 15° east, 

 McCaskey " estimated the thickness of the entire iron-bearing 

 bed at Constancia, which was opened by pits at the time of his 

 visit, at about 5 meters. Quartz is not as conspicuous here as 

 elsewhere; pyrite is noticeable, especially in the altered walls. 

 Massive magnetite is the principal vein mineral, and occurs also 

 in the walls as grains in a mixture of finely fibrous, light-colored 

 amphibole which Eddingfield identified as tremolite. 



THE SANTOIi ORE DEPOSIT 



At Santol about 4 kilometers southwest of Hison, iron ore is 

 again encountered. Numerous large bowlders of hematite are 

 strewn over the lower slope of the steep northern wall of the 

 valley of Santol Creek about 500 meters upstream from Puning 

 Cave. The ore is hard, and carries considerable quartz as a 

 filling between grains of hematite and in veinlets through the 

 ore. The larger part of the hematite is massive, but specularite 

 is also present. Some ore is found on the upper slopes 150 

 meters above the level of Santol Creek, but most of the bowlders 

 and especially the large bowlders, some of which weigh a number 



" Loc. cit., 50. 



