Copper ore from the Nigua valley is assayed in Paris

The valley of the Nigua, which lies upstream of San Cristobal, and all the land between el Cuayo Joina and Mano Maluei possess veins of copper. In the west, in the heights of the Nigua, the copper pyrites, which contain 25 to 30 % (per cent), seem to be formed of a great mass between 2 layers of iron; then, running toward the northeast, the veins appear distinct and well formed, like quartz gangues enclosed in the ancient schists. One finds there green and blue carbonates of copper, oxides, pyrites and fatty, silver-bearing copper. This ore gave, in the analysis made of it at the School of Mines in Paris on 30 July 1885, 1,075 grams per ton.

Rouzier tells this under the entry SAN CRISTOBAL ou Saint Christophe.