vm, a, 2 Edding field: Ores of the Philippines 99 



and siliceous gold-bearing solution alone filled the fissures. This 

 was followed by a second Assuring, probably produced by the in- 

 trusion of the diorite, when calcite manganese gold-bearing so- 

 lutions ascended in the Antamok Valley section. This was later 

 followed by the fracturing of the diorite, from cooling, and the 

 deposition of calcite, free from manganese. The copper, tel- 

 luride, and lead veins probably were derived from local deposits, 

 through which the ascending solutions passed, dissolving in their 

 course the characteristic minerals. 



PARACALE DISTRICT 



The Paracale district is located in Ambos Camarines, Luzon, 

 and occupies an area of about 200 square kilometers. Some of 

 the veins are shown in Plate II. With the exceptions of the Tum- 

 baga, Nalisvetan, and Navotas groups, the veins are compact 

 quartz containing large amounts of iron pyrites with varying 

 amounts of copper. Among these are the San Antonio, Longos 

 Point, and California, of Dinaanan Ridge, and the San Mauricio 

 on May Cruz Mountain. Most of these veins show visible gold 

 in the oxidized zone. 



The Navotas veins are narrow stringers of quartz with galena, 

 sphalerite, iron pyrites, and gold. 



The Nalisvetan deposit is a pockety, silicified mass of ore 

 carrying free gold and some pyrites. 



The Tumbaga deposit is a marked exception to the ores in 

 the district. It is a contact deposit, between shales and igneous 

 rock. The ore occurs as quartz and calcite stringers carrying 

 galena, sphalerite, copper and iron pyrites, tellurides, and large 

 amounts of visible wire gold. It is very irregular and limited 

 in extent. 



AROROY DISTRICT 



This district is located south of Aroroy, Masbate. It com- 

 prises an area of about 80 square kilometers. The principal 

 veins are shown in Plate III. Calcite, quartz, and manganese 

 veins are characteristic of this district. Of these the Colorado, 

 Eastern, and Keystone are the most important. It is evident that 

 the quartz was deposited after the calcite, as shown in the 

 leached ore where only a skeleton of quartz is left outlining the 

 spaces formerly occupied by calcite crystals. 



Colorado veins. — This deposit is found in igneous rock. The 

 hanging wall is andesite. The footwall for a portion of the 

 vein at least is decidedly different, and appears to be a separate 

 intrusion. In the places opened up, the ore is quartz (partly 



