330 ^^6 Phili'p'pme Journal of Science 1915 



contact mineralization, probably at the contact of intrusive diorite 

 and limestone. The Bato-bolani and Calambayanga ore deposits 

 prove upon examination to be very much alike, except that mag- 

 netite is the predominant ore mineral at Bato-bolani, whereas 

 hematite predominates at Calambayanga. Probably the two 

 deposits are related in origin, and certainly the observations 

 recorded herewith on the Calambayanga deposit are evidence 

 of a genesis similar to that suggested by Rinne for the ore at 

 Bato-bolani. 



Certain general characteristics are common to the iron ore at 

 Calambayanga, at Bato-bolani, and in Bulacan Province:* for 

 example, the association of the ore with intrusive rocks in sedi- 

 mentaries, especially limestones ; the nature of the ore minerals ; 

 and the presence of quartz in the ore. In some of the Bulacan 

 deposits the replacement of limestone by ore is clearly evident. 



QUANTITY OF ORE AVAILABLE 



No development work which throws any light on the dimen- 

 sions of the deposit nor the persistence of the ore with depth 

 has been done on the Calambayanga ore. The only direct 

 evidence which can be brought to bear in a discussion of quantity 

 is the extent of the outcrops. But even the dimensions of the 

 outcrop cannot be determined accurately because of the fact 

 that the ore is encountered only in blocks which afford no 

 precise data as to the width of the ore in place. The size and 

 abundance of these blocks and the length of the line along which 

 they occur have led several observers to the conclusion that they 

 represent an ore body, or ore bodies, of great size. Fanning,* 

 for instance, concluded: 



The quantity of hematite cannot be estimated at the present time because 

 experience in other fields where enormous quantities were indicated on the 

 surface shows that they may not be realized at depth. Whether or not 

 this will be true for this formation is a matter for future development 

 to determine. * * * The surface indications are excellent, yet the 

 amount and quality of the ore are unknown. It is unquestionable, however, 

 that the property is worthy of extensive development. 



Adams, also, examined the Calambayanga deposit and com- 

 mented on it as follows:® 



A deposit of iron ore in the form of a dike cutting sedimentaries is 

 found on a small island in Mambulao Bay. It continues on the mainland 



*Dalburg, F. A., and Pratt, Wallace E., This Journal, Sec. A (1914), 

 9, 201. 



'^ See footnote 2. 



'This Journal, Sec. A (1911), 6, 463. 



