170 ' IDDINGS. 



Granite is rather an uncommon rock, so far as present observations go, 

 and the few bodies of granite known are somewhat metamorphosed, or 

 altered. 



That found near Paracale, Ambos Camarines, has a gneissoid texture, is medium 

 to fine grained, and consists of white feldspar and quartz and darkgreen chloritized 

 mica. It is inequigranular, with equant anhedral feldspar and quartz crystals, 

 with smaller amounts of intersertal anhedrons of the same minerals, besides 

 chloritized mica and epidote. The feldspars are orthclase, and less oligoclase or 

 albite. There is considerable quartz. 



The granite at Mambulao has been sheared to a thinly laminated gneiss with 

 "avgen-struktitr" on a small scale. The orthoclase and albite lie as anhedral 

 blocks in a matrix of smaller equant anhedrons of quartz and orthoclase, with 

 shreds of muscovite, having pronounced fluxion structure. 



Peridotites occur at various localities on Luzon in association with 

 gabbro, and probably some pyroxenite. They are mostly altered to ser- 

 pentine. 



On Grande Island, Subig Bay, there is medium-grained periodite with consertal 

 fabric. The component crystals are anhedral, and consist of pale-green augite, 

 and faintly pleochroic hypersthene, colorless olivine, some green hornblende inter- 

 sertal with respect to the other ferro-magnesian minerals, and some plagioclase, 

 at least as calcic as labradorite. The two kinds of pyroxene are interlaminated in 

 some crystals, and some hypersthene is poikilitic with plagioclase inclusions. 

 There is no magnetite. 



Another peridotite quite similar to that from Grande Island, occurs at Malitbog, 

 on Leyte. It contains much partly serpentinized olivine; also some dark brown 

 intersertal mineral in small anhedrons, which appears to be garnet. 



Highly serpentinized peridotite occurs at Mambulao, Camarines Prov- 

 ince, and also in Ilocos Norte;, in Albay, and elsewhere. 



In Ilocos Norte there are chlorite rocks ; some with epidote, others with 

 rutile, actinolite, and muscovite. Their origin is not at present known. 



On Mindanao there is a laminated, sheared rock composed of fragments 

 of hornblende and pyroxene, without feldspar, which appears to be sheared 

 pyroxenite. 



