Annual Report of the Secretary of the Interior for the year ended June 30, 1897 . from north to south through Sierra County. With the subjacentlimestone it dips to the east, underlying the placers proper, which are inall probability made from its partial denudation and small fortunes have been made by discovery of and following richstreaks in the conglomerate, but to make available the immense treas-ures of this deposit larger operations are needed. As in the similarconglomerate reef of South Africa, the ore must be mined and reducedon a large scale to be profitably handled
Annual Report of the Secretary of the Interior for the year ended June 30, 1897 . from north to south through Sierra County. With the subjacentlimestone it dips to the east, underlying the placers proper, which are inall probability made from its partial denudation and small fortunes have been made by discovery of and following richstreaks in the conglomerate, but to make available the immense treas-ures of this deposit larger operations are needed. As in the similarconglomerate reef of South Africa, the ore must be mined and reducedon a large scale to be profitably handled. The average value of thematerial and the cost of bringing sufficient water to its reduction arematters easily to be ascertained, and with the accelerating pursuit ofgold we may expect to soon see these fields assume a national importance. The quartz veins of the Hillsboro district are of the kind known asdike fissures. Igneous dikes course through the surrounding trachyteformation in a general northeast and southwest direction. The ore is , St. Francis Cathedral at Santa Fe. TERRITORY OF NEW MEXICO. 501) found generally on the eastern side, and is composed of quartz withpyrites of iron and copper carrying gold and silver. About 4 ouncesof silver to 1 ounce of gold is the usual proportion in which the preciousmetals are found, and from 1 to 10 the usual percentage of copper. Atthe surface, and to a considerable depth in some of the mines, the oreis thoroughly oxydized, so much so as to constitute a free-milling ore;and where it exists in sulphide form it is a good smelting variety, freefrom zinc, and commanding favorable rates and low charges. About two hundred claims have been located in this district. Ofthese only five have been worked to a depth exceeding 200 feet. Threehave shafts of between 350 and 500 feet. Of these five mines two haveshown an increased value of ore as depth has been gained. Untilrecently only those mines which showed pay ore at the surface wereworked, b
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