FIFTEENTH ANNUAL REPORT 55 



Geology of Bulacan; iron deposits, Philippine Journal of Science, Sec. A 

 (1914), vol. 9, No. 3, 201-262. The Bulacan iron deposits, Mineral Re- 

 sources P. I. for 1909 (1910), 32-33; for 1910 (1911), 57-60; for 1911 

 (1912), 39-41. A geological reconnoissance of the iron region of Angat, 

 Bulacan, Bull. P. I. Min. Bur. (1903), No. 3, 1-62. Iron ore in Surigao 

 Province, Phil. Journ. Sci., Sec. A (1915), vol. 10, No. 5, 335-347. Investi- 

 gation of iron-ore deposits in Surigao, Mindanao, Bureau of Science press 

 bulletins 36 and 39. 



PHILIPPINE BUREAU OF SCIENCE CHART 10 

 MINOR MINERAL RESOURCES 

 [See prints in photograph stand.] 



Asbestos. — Asbestiform minerals are widespread in the Philippines. 

 They occur associated with serpentine, which has been found in Ilocos Norte, 

 Bataan, Antique, and Albay Provinces, Luzon. 



Manganese. — Manganese occurs as psilomelane, pyrolusite, and wad in 

 Ilocos Norte, Pangasinan, Bulacan, Tarlac, and Masbate. Three thousand 

 tons of manganese were mined in Ilocos Norte and shipped to Japan in 1916. 



Guano and phosphates. — Bat guano occurs in caves in nearly every 

 province. Much of this is valuable as a fertilizer, and it has been used to 

 great advantage on sugar cane fields. The guano can be delivered to any 

 plantation for a fraction of the cost of commercial fertilizers. One planter 

 in the Silay district, Negros, increased his crop nearly 100 per cent by 

 the use of guano. An area of leucite-tephrite, a potash-bearing rock, which 

 may some time become a source of potash, has been discovered and mapped 

 near Aroroy, Masbate, by the Bureau of Science. Apatite, a calcium phos- 

 phate, found in Ilocos Sur, may indicate a commercial source of phosphates. 



Salt. — The salt manufactured in the Philippine Islands each year is 

 valued at more than $250,000 (^500,000). Sea water evaporated by solar 

 heat is the source of the larger part of this production, but in certain 

 localities, notably north-central Luzon, brine from salt springs is utilized. 



Other Philippine mineral resources are fire clay, abrasives, alum, artesian 

 and mineral waters, gems, and gypsum. 



REFERENCES 



The asbestos and manganese deposits of Ilocos Norte with notes on the 

 geology of the region, Philippine Journal of Science, Sec. A (1907), vol. 2, 

 No. 3, 145-177. 



Manganese deposits of the Philippine Islands, Mineral Resources P. I. 

 for 1911 (1912), 42-47. 



Philippine guano, Phil, Journ. Sci., Sec. A (1912), vol. 7, No. 3, 195-199. 



The salt industry and resources of the Philippine Islands, Mineral 

 Resources P. I. for 1911 (1912), 63-75; Merchants' Assoc. Rev. (1911), 

 vol. 1, No. 10, 2-8. 



The occurrence, composition, and radioactivity of the clays from Luzon, 

 Phil. Journ. Sci., Sec. A (1908), vol. 3, No. 5, 377-389. Philippine pottery, 

 Phil. Journ. Sci., Sec. A (1910), vol. 5, No. 2, 143-153. The non-metallic 

 minerals, Mineral Resources P. I. for 1907-1912 (1908-1913). Water 

 supplies in the Philippine Islands, Phil. Journ. Sci., Sec. A (1914), vol. 10, 

 No. 4, 273-411. Miscellaneous non-metallic mineral products. Mineral Re- 

 sources P. I. for 1909 (1910), 43-52. 



