ECONOMIC GEOLOGY OF THE BAGUIO DISTRICT. , 435 



formerly extended over this central region in a great arch, as shown in 

 the ideal section (Fig. 1). 



The fissures now occupied by the veins seem to follow some definite 

 system, northwest and southeast, and they doubtless have, in turn, some 

 definite relation to the torsion set up during the uplift of the region. 



In the Bued Eiver I noted the Jointing in the andesite as follows : 

 One system running north 15° west and another north 38° east. I have 

 not found any special correspondence between these systems and the veins 

 of the district. However, there seems to be some general similarity 

 throughout the different parts of the Archipelago in the matter of the 

 larger fissures; namely, that the noi'thwest and southeast system is the 

 major one. (W. D. S.) 



THE MINERAL VEINS. 



The types of mineral veins. 



1. Calcite and quartz, with manganese, galena, iron, and free gold: 



a. Headwaters. A vein 5 to 8 meters wide in the west; high in 



calcite usually on the hanging wall, carrying some pyrite and 

 galena. In the east, quartz manganese on foot and hanging walls, 

 often barren between. Values irregular, in large lense-like masses. 



b. Camote. Characterized by ribbon or banded structure of calcite, 



and manganese; with granular segregations of quartz throughout, 

 irregular in a vein 8 to 15 meters wide. Very large amounts 

 of maiiganese make the vein very black. 



c. Gomqk. Mostly calcite with some galena in an irregular vein. 



Marked banded structure with considerable manganese and in 

 places some galena and copper. 



d. Antamok Valley. Calcite gangue banded with manganese; veins 



1 to 1.5 meters wide. 



e. Madison. Several nearlj' pure calcite veins, in some cases showing 



a marked banded structure due to manganese. 



2. Quartz veins with some pyrite and free gold and in some cases manganese, 



galena, or copper : 



a. Kelley (south slope). A much oxidized quartz vein 3 to 10 meters 



wide with rich streaks throughout; indefinite walls. 



b. Muyot. Strong vein 3 to 6 meters wide with some rich streaks and 



in places abundant sulphides. 



c. Major Mines. About one-half of these veins are of this type. 



Some are mainly quartz and free gold, and some show quartz 

 bands with horses of country rock between. 



d. Emerald Creek. Much oxidized veins with large amount of man- 



ganese and iron. One vein is said to be 15 meters wide at 

 the lowest point. 



e. Batwaan. Veins from 1 to 1.5 meters in width with hard bluish 



quartz as gangue. Sulpliides abundant. Some galena present. 



f. Madison. Brecciated quartz with manganese. Vein varies in width 



from 1 to 5 meters. 



g. Antamok. Several quartz veins, granular and loose near the surface, 

 h. Inca. Very wide quartz vein, a stringer of calcite. 



