X, A, 3 



Smith: Reconnaissance of Mountain Province 



179 



gives a bird's-eye view of the broad valley of the Abra. The formation 

 along the ascent is always a friable trachyte. Toward the east lies the 

 lofty Data, covered with thick forests of oak trees; according to C. Semper 

 this mountain is "an extinct volcano fallen to ruin." There is supposed 

 to be a small lake at the summit. Formerly Mancayan was the scene of 



Fig. 1. Outline of northern Luzon, showing region traversed. 



extended copper mining, which, however, at present has almost entirely 

 ceased. The ores were already known to the Igorots and were worked by 

 them before the coming of the Spaniards. The courtesy of two Spaniards, 

 who were kind enough to clear away the old rubbish heaps [tailings and 

 gangue] made it possible to obtain an idea of the occurrence of the ores; 

 I also went through several of the galleries myself. The copper minerals 

 occur in a quartz lens found in the sanidine-trachyte, which lens as a whole 



