NORTHWESTERN PANGASINAN. 217 
TABLE III.—Analysis of manganese." 
Constituent. Per cent. 
Manganese (Mn) > 58.58 
Tron (Fe) 0.55 
Phosphorus (P) 0.100 
Alumina (Al) 0.388 
a Analyzed by T. Dar Juan. 
b Equivalent to 92.5 per cent manganese dioxide (MnOz). 
This shows an excellent grade of manganese ore, but the 
deposit is so superficial and limited as to be of no commercial 
value. 
While it is obvious that the ore has resulted from the weather- 
ing of the rock, its occurrence and origin there is not yet known. 
The fact that the manganese is found on the surface of the 
ground adjacent to the line of fracture and close to the cherts 
suggests that the submarine springs which produced the cherts 
were the agencies which brought the manganese to the sedimen- 
taries or andesite. Analysis of the cherts revealed the presence 
of manganese and it is possible that the precipitation of the 
silica was accompanied by the simultaneous precipitation of the 
manganese. 
It is impossible to state where the springs originally obtained 
‘the manganese, but it is feasible to assume that the waters per- 
colating through the andesite dissolved some manganese in pas- 
sage. A striking example of this process was seen in the water 
flowing into Taal Volcano subsequent to the eruption of March, 
1911. This water in passing from the lake surrounding the 
voleano through the andesite forming the sides of the crater 
gained in manganese content from a trace to 79.9 parts per 
million.2* 
NONMETALLIC DEPOSITS. 
Road-building material—At San Isidro in the southeastern 
corner of the area, a quarry was opened for the extraction of the 
andesite for road construction. This rock was used on the road 
from Dagupan to Lingayen which is: known as one of the best 
roads in the Philippine Islands. The quarry was abandoned 
upon completion of the Lingayen road, but will probably be re- 
opened when more road-metal is required. The quarry is located 
on the Agno River close to the sea, and might be considered a 
source of metal for the streets of Manila. However, the cost 
of transportation and the uncertainty of smooth water during 
much of the year make this seem unfeasible. 
* Cox, Alvin J., This Journal, Sec. A (1911), 6, 96. 
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