The Arizona sentinel., 1902-10-01
LA FORTUNA MINE.

In the early days of gold discovery of Califor- niR lS4S, when the news reached the gold miners Of Sonora, there was general exodus of the Ahle-b bodied men who were able to get away northwest to the new Fl Dorado m California and the state of Sonora contributed many men to the mining population They took the old road which was known as the ''camlno real from Estancia and Altar northweStward, nearly parallel to the gulf. following the mountain ridge known as the Gila range, just north of our present boundary. The road led to Yuma and in passing the t1ila range they went within few feet or yards of a very modest outcrop of quartz which no one seemed to consider of sui fcient value to merit any attention. That hum ble and insignificant quartz outcrop is today the outcrop of the great Fortuna mine.
 It is situated on the westward slope and nearly at the base of the range of mountains called on some of the old maps the Gila range. This trends northweSterly and reaches nearly to the Gila river at the point now known as BlaiSdell. The railway in its course to Yuma passes around the northwest point of this range. Where the rocks are exposed at that point they are mostly of homogeneous granite, of gray color and weathered out at She surfaces which, however. are much pitted as if hv decompoSi- tion of some soft substance. But beyond these iow-lying hills of granite there are big outcrops of rock which to the experienced eye indicate Stratified formations They are indeed strait fed, for the bulk of the range Southward and southeastward is composed of regular stratifed, laminated. hard gneiSSic rock. use the word '-gneisSic' in a very general and comprehensive senSe for you can describe these rocks with much more accuracy if you localfZe them as
 
 polationS of quartZite beds, especially in the upper part of the series with green stains, SUD- posed to be stains of copper and decomposition of copper ore. which they probably are, al- though there are peculiaritieS of color, and some yellow colOrS, which indicate to me the presence of some other mineral, possibly, tel iurium. which by its decomposition has given these colors. The fact remains, however, that the bullion from the upper part Of the vein con- tains more copper than 1t now contains in the lower levels of the mine. The workings which carried a condition of things which could not be foretod from an inspection Of the outcrop- The vein or lode appears to be chimney, not a contino- ouS ore body, nor continuous vein with an ore body or chimney or chute upon 1t. As re- marked the outcropping points indicate that there IS no very great longitudinal extension of this ore body.
 The vein is remarkable first in this limited out crop; second in its continuity in depth it's con tinued satisfactory richness, and the promise it gives Of enrichment by further veins dipping nto it on the foot-wall sides.
 Some facts in regard to the product or yield :: The ore paid from the surface. The product or ore extracted up to the time has been about 80 tons per day, which is sent to the 20Stamp mill, each stamp of which crushes about tons in every twenty-four hours. The extraction is chlehy and largely by power drills force of so men is employed by this mine and mill. The greater part of the labor underground and mining is done by compressed air. The lode, was told. was to l5 feet wide. This large space permits the use of power drills 10 great advantage. In the material hoiSted there are fragments of the wall rocks, some of which are thrown out, but many pieces pass through the mill. They would prefer to reject most of this wall rock. but 1t would take more time and eX- penSe than 1t does to mill it, and there is a chance of some of it containing gold. From these 30 tons of rock crushed daily the average product is perhaps SIS 600 worth of gold peI month. Some months they have produced as high as 800 900.
 In the region of the Fortuna mine the forma nonS appear to be wholly of mica slate ana hornblende slate, with some arenaceoUS layer; Ike old micaceous sandstones and quartzites The mine k surrounded by black hOrnblendi, states and mica Slates, dipping SouthWard anC SOuthweStward at an angle of about 45 degrees and these states are very evenly laminated ridge after ridge.