Mar. 1899. THe Ores or CoLomBiA—NICHOLS. 147 
This is a mixture of a black, compact quartz with much blende, 
considerable pyrite and small quantities of galena. Large inclusions 
of trachyte are in some instances replaced on the outside by a fine 
granular mixture of sulphides and quartz. There is some evidence 
that much of the sulphides of the specimen have replaced angular 
trachyte fragments. 
‘*r70A. Concentrates called /aguas from the Zancudo mine.” 
Jaguas are the highest grade of the five classes of concentrates 
from this establishment. According to Sefior Don I. Gutierrez de 
Lara, they contain 50 per cent. quartz and 50 per cent. sulphides. 
‘771, [E 1072.] Ordinary ore from the Paz level of the Zan- 
cudo mine.” 
Like No. 169. 
‘172. Pyrites, galena and blende, scheiderz from the Zancudo 
mine.” 
‘«173. Pyrites, galena and blende, schezderz from the Zancudo 
mine.’’ 
‘©7174. [E 1635.] Ordinary ore to be broken and sorted into 
two qualities.” 1 
This is a quartz impregnated with sulphides, with zones of pure 
sulphides at contacts with an altered trachyte. 
“175. [E 1075.]| Schezderz from others’ workings in the Rosa- 
rio and Paz levels of the Zancudo establishment.”’ 
This is an example of ores taken out by independent miners who 
lease the privilege of working those parts of the mine which are not 
profitable when worked in the regular manner, 
This specimen is a trachyte breccia largely replaced by blende, 
galena and pyrite in quartz. The blende is in great excess, 
‘776, Pyrites and blende, schetderz from the Chorros vein of 
the Zancudo establishment.” 
‘«178. Ordinary ore from the Chorros vein of the Zancudo 
establishment.”’ | 
‘179. Schetderz from the Chorros vein of the Zancudo estab- 
lishment.” 
‘*180. Molino ore from the Chorros vein of the Zancudo estab- 
lishment.” 
“181. [E 1076.] Crystallized pyrite from the Chorros vein of 
the Zancudo establishment.” 
Here large pyritohedrons of pyrite occur on an altered trachyte. 
Blende crystals of the usual irregular form of later growth mingle 
with and partially cover the pyrite. Sharp crystals of blende of 
earlier growth occur in peculiar forms. Mingled with the quartz 
druse are needles of arsenopyrite. 
