NORTHWESTERN PANGASINAN. 279 
TABLE V.—Free-sand determination on Sample No. 1.* 
Constituent. Per cent. 
Feldspar 75.09 
Silica (in feldspar ) 61.21 
Silica (soluble) 7.94 
Total silica (SiO.) 69.15 
Alumina (AI.0O; in feldspar) 13.88 
Silica (In quartz and feldspar) 61.12 
Quartz feldspar 75.00 
3 Analysis by Forrest B. Beyer, division of general, inorganic and physical chemistry. This 
analysis was approximate and may vary from 1 per cent to 2 per cent. Free sand was absent. 
Sample 2 came from the sedimentaries at Abu and was taken 
from near the bottom of a well 3 meters deep. In hand speci- 
men the rock is light gray, and exceedingly fine-grained except 
for a few minute fossils. The rock effervesces with acid. The 
chemical analysis indicates a marl, and under the microscope 
the rock is seen to be tuffaceous in character. A thin section 
shows an exceedingly fine-grained rock with glassy structure. 
Occasional grains of magnetite and fragments of tremolite and 
feldspar are present. The minerals are much decomposed and 
under crossed-nicols the slide is mainly isotropic except for 
innumerable tiny stars of doubly refractive, crypto-crystalline 
minerals, probably feldspars. The magnetite is somewhat 
decomposed. 
Sample 3 came from a small knoll at Abu, within 0.5 kilometer 
of sample 2, and represents the same horizon. In appearance 
and under the microscope this sample is similar to sample 2. 
Further analysis of sample 3 showed the following: 
TABLE VI.—Analysis of Sample No. 3.* 
Constituent. Per cent. 
Soluble silica in hot hydrochloric acid 0.65 
Soluble silica in sodium carbonate 15.70 
Silica as free sand 1.53 
Total silica undetermined 
Sulphur 0.10 
8 Determined by T. Dar Juan according to specification of Bleiniger, Ohio State Geological 
Survey. 
As indicated by the intercallations seen in the field, variations 
of high and low silica and calcium are revealed by analysis. 
The average is low in calcium, which deficiency could be met by 
the use of coral from the elevated reefs of Alaminos or south 
of Balincaguin. The purity of this coral is shown by analysis 
No. 4. 
