ECONOMIC GEOLOGY OF THE BAGUIO DISTRICT. 445 



SUMMARY. 



1. The rocks of this region comprise sedinientaries, volcanic breccias, 

 metamoi-phic rocks, intrusive and extrusive igneous rocks of Tertiary and 

 possibly Mesozoic age. 



2. The principal rock is andesite, a lower and an upper formation se- 

 parated by sedimentaries. 



3. The gold veins are largely fissure veins in the lower intrusive an- 

 desite. 



4. This lower andesite grades imperceptibly into diorite. 



5. This is a region of steep slopes and excessive rainfall (38 inches fell 

 in 34 hours on the 15th day of July. 1911, in Baguio). 



6. By reason of this excessive rainfall, steep slopes and the geologic 

 conditions of the andesite on the upper slopes of the Benguet caiions the 

 building of highways along the bottoms of the gorges has involved, and, 

 until these slopes are reduced to a lower angle, will involve great en- 

 gineering risks. 



7. Gold is the principal mineral of economic value. 



8. The ores for the most part require the cyanide process. 



9. Theie are 25 stamps in the district, distributed through 4 mills. 



10. There is only 1 cyanide plant in operation. 



11. Manganese is secondary in the veins and is characteris^tic of the 

 district as a whole. 



18. The values are very irregularly distributed in the ore bodies. 



13. No mine has yet gone below water level. 



14. The gold production for 1910 amounted to 95,960 pesos. ■ 



15. There are noteworthy ore bodies here but for the most part they 

 are not developed. 



16. Consolidation of properties would be advisable. 



17. Better power facilities are needed. 



18. The timber question will shortly be a serious one. 



19. Capital is badly needed. 



20. Materials for making lime, sand-lime, and clay bricks, for glass 

 and pottery glaze are available in the district. 



21. The production of nonmetallics has been negligible. 



22. Good road materials exist in this region. 



23. Limestone is particularly good for this purpose on account of its 

 high cementation pioperty, but the best material so far found is a diorite 

 containing secondary calcite as a result of incipient decomposition. 



106090 2 



