﻿BENGUET PETROGRAPHY. 



241 



such as diopside or actinolite. One or two very large patches of calcite 

 make it appear quite probable that some calcium has been introduced 

 from the outside. 



Magnetite constitutes fully 10 per cent of some of the slides of this 

 rock. There is also a small amount of pyrites. 



Table II. — Benguet No. 16. 



Constituent. 



Per 

 cent. 



Molecu- 

 lar pro- 

 portions. 



Orth. 



Alb. 



Ac- 

 mite. 



Diop. 



Hyp. 



Oliv. 



Si0 2 — 



A1 2 3 . 

 Fe,0 3 . 

 FeO— 

 MgO_. 

 CaO— 

 Na,0- 

 K 2 0„. 

 H,0... 



49.89 

 1.87 

 2.61 



23.47 

 6.57 



10.75 



2.01 



.09 



3.53 



832 

 019 

 016 

 326 

 164 

 192 

 032 

 001 



108 

 18 



384 



260 



18 



128 

 64 

 192 



193 

 87 



IS 



Constituent. 



Norm. 



Orthoclase. 



Albite 



Acmite 



ICa.. 

 Diopside <Mg— 



lFe_. 



(Mg- 



IFe.. 



(Mg.. 

 " IFe- 

 Magnetite 



Hyp. 



Oliv. 



.001 

 .018 

 .014 

 .192 

 .067 

 .128 

 .087 

 .173 

 .006 

 .021 

 .002 



°- 56 l F 9.99 Sal 9.99 

 9.43) 



6.47\ 



6.47 

 22.27 



6.40 

 16.90 



.701 



.84) 

 .841 



3.561 



22.84) 

 3. 



45. 57 



31.54 

 4.40 



.46 



P 83. 58 



4.40 

 M .46 



> Fern 88.44 



Class V. Perfeuiane. 



Subclass I. Perfemone. 



Order 1. Maorare. 



Section I. Caroliniare. 



Rang 1. Websterase. 



Subrang 4. ( Do f errous. ) 



BENGUET NO. 150.— GRAYWACKE. 



Macroscopic. — Is an aphanitic, medium-grained, hyp-automorphic 

 granular rock of a speckled white and green color. This rock is not very 

 unlike a coarse-grained sandstone. Feldspar is practically the only 

 mineral distinguishable with the naked eye. 



Microscopic. — This is unmistakably a fragmental rock, but it is not so 

 easy to say positively whether it is a normal sedimentary derived from 

 land wear or of pyroclastic origin. Under the microscope one sees a 

 confused mass of minerals, some rounded and some angular, consisting of 

 quartz, orthoclase, plagioclase, magnetite, chlorite, and numerous saus- 

 suritization products such as qu? ,z, epidote and possibly calcite. Under 



