THE GEOLOGY OF Li ON, PI. 61 
tantalizing and have been the ruit of more than one over- 
enthusiastic miner. In these veins the Zangue is mainly a cellular 
quartz. There is also enough zinc ~ -d lead to complicate the 
process of treating these ores. Very l tle manganese is to be seen 
in these veins and the striking fact to be noted here is this, that this 
is the best placer district so far found in the whole archipelago. 
COPPER 
Copper has been found in the form of arsenates and sulphides 
in the Mancayan-Suyoc district of the Mountain Province, Luzon 
and the Camarines. The best known deposit is that in the 
Mancayan-Suyoc district. Eveland' writes the following con- 
cerning this deposit: 
In view of the fact that the entire region, with the exception of the one ore 
body of the Mancayan mine, is in an early stage of development, it is impracti- 
cable to treat the ore deposits in detail. It seems to be fairly conclusive, 
however, that the general type of vein in the district is a narrow quartz lead, 
carrying metallic sulphides, in some cases of copper, and generally with gold 
associated in a free state. These veins are in the Mancayan diorite which 
underlies the entire district. With the advent of the “‘trachyte”’ flow, meta- 
morphic changes have taken place and the nature of the country rock is altered 
to a considerable degree. 
Recent development work has shown this deposit to be rather 
in the nature of a stockwork, and it appears to me to be more 
extensive than was first thought to be the case. 
tA. J. Eveland, Bulletin No. 4, Min. Bur. Manila (1905). For further data 
regarding the mineral resources of the Philippines the reader is referred to the annual 
bulletin Mineral Resources of the Philippines, issued by the Division of Mines, Bureau 
of Science, Manila, P.I. 
