110 ADAMS. 



The Sisiman quarry was developed in a small hill which in its central 

 portion exhibits a massive columnar structure such as is found in the 

 volcanic neck and stock. This structure was favorable to the quarrying 

 of large stones which were needed in building the breakwater. A crush- 

 ing plant was established for supplying crushed stone and a considerable 

 quantity has been used in concrete construction in Manila. 



Basalt. — During the Spanish regime a quarry was opened on a small 

 peninsula near the town of Binangonan and some paving blocks were 

 cut at localities near by. The quarry had too small a face to warrant 

 development on a commercial scale, and, moreover, the rock was variable 

 in. texture. Some stone was obtained from the locality when the im- 

 provement of the streets of Manila was begun by the Americans, but 

 in a short time they transferred quarrying operations to Malagi Island, 

 which was then used as a prison. 



Certain textural varieties of this basalt are employed for making small 

 stone mills such as the natives use for grinding and hulling rice. 



The city of Manila opened a large quarry at Subay in the northeast 

 part of Talim Island, and this has been the principal source of nearly 

 all of the stone used in macadamizing Manila streets. There the basalt 

 occurs in the form of a flow, but it is of variable texture, portions of it 

 being vesicular and somewhat scoriaceous. This has rendered it difficult 

 to obtain an even product, and the city requested the division of mines 

 to look for a more suitable location and a better stone. 



Qabbro. — The Spanish authorities established a quarry southeast of 

 Angono for the purpose of obtaining stone for riprapping a part of the 

 Pasig Eiver banks near Pasig and building a short breakwater for Ma- 

 nila Harbor. The records show that they installed steam drills and a 

 tramway to the border of the lake and built a stone pier to facilitate 

 the loading of scows by dumping from the tram cars. All the equipment 

 was sold and the quarry abandoned before the American occupation. 

 The stone pier remains to mark the termination of the tramway and by 

 following inland, the quarry may readily be found. The rock is a brec- 

 ciated gabbro, suitable for rough stone or crashed stone for concrete 

 work, but it is not well suited for macadamizing roads. A new quarry 

 site has been selected by me to the northeast of Angono, where the 

 gabbro is of even texture. The stone at this place is probably the best 

 which can be obtained for use as road material in Manila, and the city 

 is making arrangements to open a quarry there and abandon the one now 

 in operation at Talim Island. 



In addition to' the quarries above mentioned, considerable stone is 

 broken up by hand on Talim Island and Binangonan Peninsula. It is 

 sold for macadamizing roads near the border of Bay Lake. Formerly a 

 quarry was operated at Los Banos by 'the Army when the road from 



