The Arizona sentinel., 1900-12-12
CASTLE DOME DISTRICT.

The veins of the Castle Dome district may be
 said to have been rediscovered in 1863 fer it was | evident that they had been anciently worked, as already stated in the historical introduction. The metal had been taken out from many of the veins by the ancient miners down to a depth of from to l5 feet and in continuous lines of | trenches, in some places for 50 to 100 feet or more. These old workings were found to be safe guides to good metal bearing ground a short distance deeper. Well worn trails leading of from these pits to the banks of the Gila | river, some IS miles distant, and the ruins there of some rude smelling furnaces, indicate that the ores were carried to the Gila, probably on the backs of Indians, and that they were smelted there, whether by the Aztecs or the early-arriving Spanish explorer is not known. Since 1863 these mines have been worked almost continuously, and are now yielding Silver-lead ore of most excellent quality, which is shipped to San Francisco. The claims were worked by the prospectors without capital until October. 1870. Up to January 1, 1892, there had not been an investment of over $500 in building or per manent improvements. The climate is such that men can work the year round without no more protection than is afforded by brush, huts or tents.
 1uC NSIIlS crop out on q plalQ or mesa at the base of the Castle Dome range, a very rugged and picturesque group of mountains trending northwest and southeast rising near the center to the remarkable d0me-shaped sum init with precipitous sides. looking like a huge round castle or building with a dome. It is a noted landmark, being visible from great dis tance in all directions. It was originally called Capitol Dome by the officers at Fort Yuma in 1853 from the fancied resemblance to the dome of the capitol at Washington. This mountain range, being but sparingly watered, has never been convenient to prospect and very little is yet known of its structure or mineral value. The mines are usually reached from Yuma by driving to Cila City and thence to the mine from 16 to IS miles east and inland from the river. The claims are numerous. Some have been patented and worked to a depth of 300 feet or more. The veins are re- markedly regular and well formed The ore is galena, carrying about 30 ounces of silver to each ton. The veins trend in general northwest and southeast course and are nearly vertical. The outcropS are in- dicated by outlying masses and weather worn crystals of fiourSpar. which is the chief veinstone. Calcite and gypsum are also found, and in some of the veins there is a vein- stone of quartz dispersed in sheets or combs along the walls or in distinct sheets in the center. Manganese spar and barite are also as- sociated in layers. The thickness or power of these veins is usually from to feet, sometimes from to 12 feet, wide. There are veins also only few inches in width In general the veins are well filled with ore. This ore occurs in sheets or punches scattered through the vein- stone and commonly known among the miners as ball metal. In one mine in the district mass of nearly solid ore feet thick was found.
 At or near the water level, where the gaIenite has decompoSed, both carbonate and sulphate of lead are found associated with pale-green fuorite and an abundance of cryStallized yellow wulfenite, another occurrence giving evidence of the presence of molybdenum in galenite.
 The rocks of the district are compact fine grained mica and clay states standing nearly on edge and traversed by numerous dilzes or intru- siVe masses of chocolate-colored porphyry.