RECONNAISSANCE OF MINDANAO AND SULU : III, 393 



families in and about the town of Surigao possess heirloom nuggets, 

 some as large as a twenty-dollar gold piece, which were obtained in the 

 Surigao gold fields in by-gone days. But few people at the present time 

 are engaged in this business continuously, and these, working on a small 

 scale and with the crudest facilities, make but little more than a living 

 from their operations. Cansuran Creek, from its junction with the Biga 

 to Mount Binutong where it rises, everywhere shows signs of old work- 

 ings in the form of excavations, ditches, and ground sluices. Great 

 quantities of large boulders, generally chloritized or serpentinized, and 

 smaller ones consisting almost entirely of quartz, are to be found in the 

 bed of Cansuran Creek. The banks of the stream are for the greater 

 part slate, striking approximately north 66 west and dipping at varying 

 angles but usually toward tlie northeast. Going toward the south or 

 head of the creek, the slate becomes more and more altered by chloritiza- 

 tion and folding, with the development of prominent and important 

 cleavage planes. 



The benches that are worked are as a rule situated 10 to 30 meters 

 above the creek, and the gravel, which appears to be the result of surface 

 disintegratiofl and erosion of the country rock, consists mostly of chloritic 

 schist, this being also the base rock of the ground sluices. 



Numerous igneous boulders are to be found in the gravel and the 

 origin of these is accredited to Mount Canmahat, a prominent conical 

 hill arising from the valley of the Surigao Eiver near the head of Can- 

 suran Creek, to an elevation of about 180 meters above the creek. This 

 hill has all the appearance of a small extinct volcanic cone; the summit 

 and upper slope are composed entirely of andesite, but about 100 meters 

 below the summit the underlying shale appears. Curiously enougli, the 

 upper courses of the underlying shale both at Camnahat and the neighbor- 

 ing hill Binutong, are less chloritized and otherwise altered than the 

 deeper seated shale. Gravel washing begins at a depth of 40 to 50 

 meters below the contact of the shale and andesite. The igneous boulders 

 are usually more numerous than those of the schistose variety, and gen- 

 erally lie above them, the latter evidently being more nearly in place. 



Gold can be panned from the surface dowm, but the colors obtained 

 from the top gi-avel are extremely fine and mostly lost by the methods 

 of mining in vogue. Most of the gold comes from the lower course, not 

 only because of the concentration which would naturally take place on 

 bed rock, but also, I think, because the gold is derived from the very 

 fine quartz and calcite stringers which so thoroughly but irregularly 

 intersect the bed rock of chloritic schist. Two varieties of gold are 

 obtained on Cansuran Creek, in varying proportions depending upon the 

 location. The one is the ordinary, rounded and smoothly worn grain, 

 while the other, somewhat lighter in color, is veiT markedly crystalline 

 and with sharp edges, and frequently contains inclusions of both calcite 



