vin, a, 2 Edding field: Ores of the Philippines 103 



tain galena and sphalerite, but no' very important quartz veins, 

 have been found in the immediately surrounding hills. There 

 is also a smaller percentage of black sand than in the other local- 

 ities of this district. 



The Paracale River placer lies in an elliptical basin covering 

 an area of several hundred hectares. The bed rock is granite 

 gneiss, and the alluvium varies from 6 to 14 meters in depth. 

 The concentrates caught on the tables of the dredge are made 

 up of about 51 per cent magnetite, 16 per cent limonite, 21 per 

 cent pyrite, and 12 per cent nonmetallic material. The gold is 

 mostly angular and crystalline; crystal trees and minute octohe- 

 drons are of common occurrence. The larger grains of gold are 

 usually attached to quartz grains. This deposit has been de- 

 scribed in detail by Fanning and Eddingfield. 12 



The Maliguit placer is found along various sections and 

 branches of the Maliguit River. It presents about the same 

 general characteristics as the Paracale River placer. 



Masbate. — The placer deposit lies in the valley of the Guino- 

 batan River, Aroroy. The gold is very fine and difficult to 

 recover. It was derived mostly from the numerous large veins 

 of calcite quartz and manganese and from small quartz veins. 

 It has been claimed that the presence of manganese in the veins 

 prevents the formation of placer in accordance with Emmons' 

 theory of the solution of gold. 13 While this may apply to a 

 limited extent, conditions are such as to justify hesitation in 

 making its application general. 



Mindanao. — Placer deposits are found at Placer, Cansuran, 

 and Lubangan, Surigao; along several streams on the eastern 

 side of the Agusan River, Butuan subprovince ; and in the valley 

 of the Pigtao River, Misamis. Of these, the Cansuran deposit 

 is of the greatest interest. The gold is very coarse and is found 

 in well-rounded grains. Some pieces have been found weighing 

 over 30 grams. The alluvium is found on the crests and sides 

 of the hills as well as in the valleys, and therefore represents 

 an old deposit which has passed through some geological move- 

 ments which raised it in part above its old bed. This deposit 

 has been described in greater detail by Eddingfield. 14 



" This Journal, Sec. A (1912), 7, 213. 



u The agency of manganese in the superficial alteration and secondary 

 enrichment of gold deposits in the United States. Bull. Am. Inst. Min. 

 Eng. for 1910 (1910), No. 47, 767. 



u Min. Resources P. I. for 1911, Bur. Sci., Div. Min. (1912), 27. 



