which was the celebrated Cerro Colorado mine. [Illustration: INDIAN TANNERY] All this portion of the Sierra Madres is unsurpassed for magnificent and thrilling views over dizzy mountain trails. At many places one could look off into infinity from a ledge not over a foot and a half in width on which the mules must walk. Occasionally a steep wall of rock rises many hundreds of feet on one side and along this the mule will carefully scrape. The descent into Cerro Colorado was the most continuous steep I ever saw. Almost before we knew it we were in the tropics again, and that by an incline where, in a dozen places, the uphill rider on one zigzag could, without taking his foot out of the stirrup, kick off the hat of one below him on the other course as he passed. Cerro Colorado is reputed to be the largest gold mine in the world, and was discovered as recently as 1888. That it should have remained so long unknown to any prospector in such a rich silver-mining district is one of the morsels of mining history, even a far greater mystery to me than that the existence of living cave and cliff dwellers on the rough mountain trails leading thereto should have been kept so long quiet. Cliff dwellers or angels in the air above them, or cave dwellers or demons in the earth under them would have attracted but little attention from a seeker of precious metals beyond the momentary astonishment at their sight. [Illustration: VIEW IN MOUNTAINS, WITH CLIFF DWELLINGS, NEAR CERRO COLORADO.] The Cerro Colorado mine is an immense buttress or spur from the flank of the Sierra Madres, the whole spur showing signs of gold, not in any distinct vein, but in great masses distributed here and there through the mountain, a sort of "pocket" system, as miners would say. This great buttress or spur is 1800 meters (something over a mile) in length, 1200 meters in breadth, and 500 meters in height, and runs from $1 to $3300 a ton, as would be expected in the pocket system of deposits. Small deposits have been found of one hundred weight or so, however, that would run enormously--over $100,000 to the ton. The gold is not wholly in pockets, for it is found distributed in all parts of the great red hill, at least in the minimum of one dollar per ton. It requires eight mines to cover the tract properly. Enormous works were being put in to develop the property, and in a few years it will be known whether this is the largest gold mine in the world or not. It is the property of the Becerra brothers, and when I visited it Don José Maria Becerra was at the mine and spared no pains to make my stay pleasant. He was then engaged in placing the most improved machinery and constructing enormous works for water power, etc. He brought out and laid on a chair four great lumps of gold, of about the value of seventy thousand dollars, that had just been run out by the Mexican _arastra_, for they were still using the ancient method of mining, awaiting the arrival of the new machinery.