108 ADAMS. 



that diori/tic rocks are present and that the iron deposits at Lanatin are 

 related to them. At the Lanatin deposits the principal ore is pyrite. 

 Assays show that the ore carries some gold. Pieces of rock which came 

 from the excavations near San Isidro showed mineralization, and on 

 fresh surfaces, well disseminated pyrite. The processes of erosion and 

 rock decay have probably liberated the gold associated with the pyrite and 

 given rise to the placer deposits. In addition to the pyrite as a source of 

 gold there may be some gold-bearing quartz veins in the eastern cordillera, 

 but in so far as now known the veins of the region are not well min- 

 eralized and no mining claims have been staked on quartz ledges. 



COAL. 



The presence of thin beds of coal in the eastern cordillera has held 

 out the hope to many prospectors that thicker beds might be found. 

 In the belt of sedimentaries associated with the limestones which pass 

 Antipolo and the waterworks gorge near Montalban, beds of coal a few 

 inches thick have been prospected from time to time within the last 

 few yeaxs, and some work has been done with the hope of discovering 

 thicker beds, but without encouraging results. Ickis records the fact 

 that coal was found in the belt of sedimentaries which he crossed between 

 Infanta and Tana}' - , but he states that it is an inferior lignite. Further 

 south in the same belt of sedimentaries coal has been found near Ati- 

 monan. On D' Almonte's map it is indicated as occurring on the Pag- 

 bilao Islands east of Lucena, but no reports as to its thickness have 

 been received in the division of mines, and there is little reason to 

 believe that it is of economic importance since, although well situated, 

 it is not mined. 



Bulacan coal field. — McCaskey while studying the iron deposits in 

 the eastern cordillera near Angat found some beds of lignite and received 

 information concerning the occurrence of similar deposits near his field 

 of work. Eecently, the division of mines has received a sample of coal 

 from the valley of the river which passes Norzagaray, and which is 

 sometimes called the Matictic. The coal seam is said to have a workable 

 thickness. It is exposed in the bed of a stream about 18 kilometers 

 from Norzagaray, and beyond that point it is found outcropping in some 

 hills. No investigation of these coal beds has been made by the division 

 of mines since the information concerning their existence was received 

 after the field work for this report was completed. 



GAS. 



In drilling wells for artesian water in the central plains region, gas 

 was encountered at Santo Tom as and at Santa Eita, a barrio of Manalin. 

 The amount at these places was sufficient to burn with a flame about 

 3 meters high when it was first encountered, but after a few days the 

 pressure diminished. The depth at which the gas was struck at Santo 



