130 The Philippine Journal of Science i»i3 



Philippine calcite ores. — The ore deposits of this type in the 

 Philippines are found in the Headwaters, Camote-Clayton, and 

 Bua mines of the Benguet mineral district; and in the Colorado 

 and Eastern mines of Aroroy mineral district, Masbate. 



The Headwaters deposit is a fissure vein in the andesite made 

 up of bands of calcite, quartz, and manganese oxide carrying 

 about 1 per cent iron pyrites and traces of lead and copper. 

 The calcite in places is about 6 meters wide, while in others it 

 is very narrow and entirely disappears near the outcrop and 

 in the vein where leaching has been extremely active. The man- 

 ganese oxides are found in bands varying from 0.3 to 1.5 meters 

 in width ; these bands are irregular, and vary from 2 to 6 meters 

 in width. The quartz is much fractured, and its sulphide con- 

 tents have been mostly oxidized in the upper levels. The calcite 

 in depth is compact and generally retains its sulphides unaltered, 

 but near the surface it is fractured, channeled, and contains 

 numerous stringers of manganese. The highest values are found 

 in the manganese bands. With depth the manganese oxide seems 

 to decrease and the calcite to increase. At and near the outcrop, 

 high values are found. These seem to decrease more or less 

 uniformly with depth. 



The Camote-Clayton deposit is at least in part a fissure in 

 andesite, but appears to follow the contact between andesite and 

 diorite for a short distance. The gangue is calcite and quartz 

 with large amounts of manganese oxides and some iron pyrites. 

 In the upper workings the calcite bands are small ; quartz bands 

 are also subordinate. The main portion of the vein is manga- 

 nese oxides (wad) including fragments of quartz and pockets 

 of crystallized quartz, which are said to contain high values. 

 The manganese bands vary in width from 4 to 12 meters. The 

 calcite increases and the manganese decreases with depth. The 

 gold values which are highest near the outcrop decrease with 

 depth. 



The Bua vein is a fissure in andesite. It is from 1 to 1.5 

 meters in width. Bands of manganese oxide make up the greater 

 part of the vein in the upper workings, but in places solid com- 

 pact bands of calcite are found. With depth, the manganese 

 decreases, while the calcite increases until it makes up the major 

 portion of the vein. The ore coritains some rhodochrosite and 

 from 2 to 6 per cent iron pyrite. The highest values are near 

 the outcrop, and are usually found in the manganese bands. 

 These values decrease with depth. 



