a ee ee. re eee ee 
—————E————— | t—st—S — ee 
624 
The gangue material of these veins varies, being for the most part 
quartz and a rock which owing to its altered condition has so far eluded 
any satisfactory classification. This second vein-stuff is greenish in 
color with brown specks of about one-third of a millimeter in diameter 
throughout the gangue. The writer is of the opinion that this rock is 
porphyritic, the phenocrysts having decomposed to give the rusty-brown 
specks. We were unable to-work out the relation of this second type to 
the quartz veins at the time of our visit to the district. Whether or 
not they branch off from the former is not as yet determined, so that 
this highly important point is left for future solution. The widest 
quartz vein which was seen, measured from 4 to 6 feet where it was 
opened up on the “Maze” claim; however, the average thickness of these 
veins as seen in the present workings and outcroppings is not over 1 foot. 
About one mile down the Calbasahan River from Camp Cronk and 
up a small tributary of the latter, termed Arizona Creek, a ledge was 
encountered which in places more nearly resembled a pegmatite than 
anything else, although on its borders it graded into the country rock, 
becoming coarser grained and more abundant in the ferromagnesian 
minerals laterally. This ledge measured 40 feet in width. The sur- 
rounding rock is decidedly gneissic. It is approximately vertical and 
strikes N. 70° W. A sample taken from a cutting across the whole 
face on assay showed only a trace of gold and 0.04 per cent of copper. 
Many of the veins in this district are vertical, but a number which 
have a varying dip of from 30° to 89° exist and in this locality this dip 
almost invariably is to the west. 
The following is a list of the minerals of economic value occurring in 
these veins: 
1, Azurite. 5. Cuprite. 9. Molybdenite. 
2. Bornite. 6. Malachite. 10. Proustite.? 
3. Chalcocite. 7. Melaconite. 11. Silver. 
4. Caleopyrite. 8. Gold. 
The black oxide of copper seems to be the chief mineral of economic 
value, although bornite in some places holds out good prospects. One 
streak about two inches wide was exposed in a tunnel in the “Reina 
Victoria” claim of Mr. Montague, which gave the highest values found 
in this district. As this streak has every appearance of widening out 
into a healthy vein, further development at that place might not be 
amiss. 
As a rule the minerals occur in little patches and pockets through- 
out the localities visited by the writer. 
Molybdenite was found to a certain extent associated with copper 
minerals, but confined more closely to the gneissic zone. It was 
nowhere seen in workable quantities. However, its discovery is very 
interesting as it is believed this is the first authentic report of molyb- 
denite from the Philippine Islands. 
