396 E. ORDÓNEZ. 
gossan exists, but in several instances iron oxides are abun- 
dant; these being accompanied with more or less copper 
ores. The old workings are naturally located on these spots, 
for instance at the mines of Magistral, Cerritos, Zapote, etc., 
however, even at these places the copper ores have never 
been sufficiently abundant to make possible a large produc: 
tion. Small lenzes containing scattered bunches or small 
masses are the common form of ore occurence even to 
deptbhs of 200 to 300 feet below the surface. Near the surface 
the ores were so scattered that the makers of the "Magis- 
tral”? were compelled to resort to a careful and painstaking 
sorting in order to obtain ores sufficiently high grade to 
warrent the necessary roasting,. 
The copper veins of the District vary from 4 to 25 feet 
in width, the bodies being always lenticular in shape, which 
lenzes are some times many feet apart. Between the lenzes 
the vein can be followed only by the fault planes or by nar- 
row stringers of quartz, with altered rock containing py- 
rite and disseminated grains of chalcopyrite. Junctions of 
veins seem in general to be favorable to ore deposition. One 
of'the best examples observed being in the Magistral Mine, 
where a junction of three veins has caused the formation of 
a series of lenzes of ore. Similar instances occur in the Ce- 
rritos opencuts and in the old mine called Timones. The 
principal veins of the district are six in number, known as 
the Magistral Veins, composed of several subsidiary veins 
close to a large dyke; following to the southeast, the Hondo 
and a vein near it; then the Timones Vein, the Monterrey 
and La Union Veins. 
Besides the Magistral, which is the principal mine of 
the District, there are three other small mines, the Ti- 
mones, Zapote and Cerritos; this last is at present being 
worked on a small scale. The Zapote and Cerritos Mines 
