RECONNAISSANCE OF SOUTHEASTERN LUZON. 463 



be traced into the adjacent fonnations. The majority of these are 

 quartz, but in the Tumbaga property calcite veins occur, carrying free 

 •gold. The calcite may have had its origin from limestones in the 

 sedimentary series. 



The ore deposits are not sufficiently studied to make it possible 

 to distinguish different periods of mineralization, but it is quite 

 probable that this can be done as development work progresses. At 

 present the veins related to the granite show the gi*eatest number of 

 old workings and are the most important. The strikes of the veins 

 of the district which were recorded fall between 5° and 40° east of 

 north. 



Most of the values of the district are the gold content of the ores. 

 The natives worked in the oxidized zone for free gold. The future 

 development must take into consideration the sulphides. These ores 

 as a rule are highly pyritiferous and contain in the different veins 

 varying amounts of chalcopyrite, galena, and sphalerite. Some of the 

 ores are probably refractory. 



Many of the veins are of good width and are persistent, while a 

 few are wide. Usually, smaller ones are associated with the important 

 veins, and some of these are said to carrj^ high values. Definite informa- 

 tion as to values in the district is not available for this report. Most of 

 the properties are not developed sufficiently to warrant detailed de- 

 scriptions. 



There is hematite iron ore near Bagacay Point, Calabornay, and at 

 Malii, occumng in the form of boulders. Probably larger deposits 

 can be uncovered at these places. 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 where there are conspicuous out- 

 crops. The strike is about north -5° west. This ore body has a width 

 of as much as 13 meters at several places. Some smaller outcrops 

 occur near by. The ore is high grade hematite and is a workable 

 deposit containing an immense tonnage. 



Placer deposits of the Paracale-Mambulao mineral districts. — It is 

 generally recognized that the gold in placer deposits of the Paracale- 

 Mambulao district has been derived from the veins. The dredging 

 ga-ound is found principally along the Malaguit and Paracale Elvers 

 and their tr-ibutaries. the Gumaus, Bulalacao, and Calambayangung 

 Rivers, and perhaps pai-ts of the intervening streams may prove work- 

 able. There is some placer gold in nearly all of the small valleys, but 

 the deposits do not warrant dredging operations. 



It is interesting in connection with the placer deposits to discuss 

 the probable submergences and emergences of this part of the coast. 

 The bed rock of the dredging ground in places is at a depth of about 

 18 meters below sea level, although iisually it is shallower. The nature 



