GEOLOGY OF THE PHILIPPINE ISLANDS. 331 



the numerous arrastres set up and operated in Ambos Camarines by 

 Spaniards from Mexico. 



The year 1905 practically marked the beginning of production in the 

 Islands under the American regime, that of gold amounting to 35,000 

 pesos (17,500 dollars United States currency). The mineral production 

 for 1909 is given in Mineral Eesources of the Philippine Islands, Bureau 

 of Science, Manila, 1910. 



THE METALS. 



Gold. — This metal has been found in some quantity in nearly every part 

 of the Archipelago. It was mined in a crude way as long ago as we 

 have any records. I have been in ancient workings on the Islands of 

 Masbate which probably were made by Chinese years before the coming 

 of the Spaniards. Magellan heard reports of gold in the Camarines when 

 he reached the Islands in 1521. Although it is not the most important 

 mineral asset of this, or, as a matter of fact, of any other country, yet 

 gold holds the first place, for it is the easiest to mine and does not 

 depend upon a market. 



The three principal districts where gold mining is now being carried 

 on are Ambos Camarines, Benguet, and Masbate. 



In the first-named district, near Paracale, mining is largely confined to 

 dredging, although Vigorous development on the lodes is in progress. The 

 country rocks are largely schistose diorites, gneissic granite, and slaty 

 shales. These formations are very similar to those found on the Islands 

 of the Karimoun Archipelago near Java. The veins, as far as we now 

 know them, are of only moderate width, but very rich; pockets running 

 as high as one or two thousand dollars United States currency a ton have 

 been encountered. Some of the values are found in the quartz filling 

 along the contact of the diorite and granite, but several good veins are 

 normal to this contact. Lode mining is farther advanced near Mambulao, 

 there being 20 stamps dropping on the San Mauricio property and a 

 Huntington mill operating on the Tumbaga. On the Paracale Eiver 

 there are two New Zealand dredges, while an xlmerican (Eisdon) dredge 

 is digging in the Malaguit. A large Bucyrus dredge will shortly be 

 installed on the Gumaus Eiver. 



The dominant rocks in Benguet are diorite and andesite, and the gold 

 is found in fairly large quartz and caleite veins in north and south, east 

 and west, and northwest and southwest systems, cutting the formations 

 indiscriminately ; that is, they are fissure veins. 



Gold occurs both native and as telluride. The ore is not entirely 

 free-milling, and cyaniding is resorted to. The chief characteristics of 

 this ore, except in one or two cases, are the general absence of manganese 

 and the adrupt change from an all-quartz gangue to all-calcite within very 

 short distances. 



