Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/449

Here I have also shown a lode to the north which was exceedingly rich. The north lode is like the main one in having the greater part of the gold in cavities in the quartz partly filled with brown oxide of iron.

The Chile main lode has been worked to a depth of about 30 yards. The "country" is decomposed talcose clay-slate. In several of the shafts which have been made on this lode, the "porfiro" or "porfido" of the miners occurs. This so-called "porphyry," also known at Chile as "quartzo morado," and "piedra morada," is a reddish, pink, or brown ferruginous hornstone, sometimes becoming jasper. It sometimes contains crystals of iron pyrites, or cavities left by their decomposition. At Chile, as shown in fig. 2, it forms a sort of lode parallel to the white quartz lode, from which it is separated by a few inches of "cascajo." The Chile miners told me that they occasionally found visible gold in it, but too little to pay them to work it. A similar rock ("porfiro") is found all over the Caratal district and is regarded by the miners as a favourable indication for gold.

A little work has been done on a lode called San Antonio, a short distance from Chile. Two "barrancos," very close to one another, have been sunk upon it, and they show a quartz lode 2 feet thick, which strikes from S. 20° E. to S. 45° E., and dips sharply to the west. The surrounding rock is "cascajo." The lode consists of quartz, with black streaks, iron pyrites, brown oxide of iron, and very fine gold.

Lying in the basin of the Yguana, like Chile and San Antonio, are the Panama workings. Much work has been done here upon loose blocks of quartz which strew the hillside, and a small opening has been made on the top of the hill upon an east and west lode. This lode is 3 feet wide in places, and dips south. On the opposite side of the valley a flattish lode 2 to 6 feet thick has furnished a good deal of quartz. Quartz has also been found and worked at the Lagunta, near Panama, and at the Independiente, between Panama and Nueva Providencia.

2. Alluvial or "placer" Diggings.— Excepting a few places on the banks of the Yuruari, the working of auriferous alluvia has at present been confined to the valley of the Mucupia and its various tributaries, such as the "quebradas," or valleys, known as the Tigre, Peru, Aguinaldo, &c.

On leaving Nueva Providencia by any of the paths to the west, we come upon pit after pit 6 to 10 yards deep; and although this ground was worked as early as 1857 and 1858, it can be pretty well seen what the diggings were like. The accompanying section (fig. 3) is made up partly from personal observation and partly from in-

Fig. 2. — Section of Quartz and "Porphyry" Lodes.

a. "Cascajo," decomposed clay-slate, b. Quartz lode. c. So-called "porphyry."