The Arizona sentinel., 1902-07-09
LA FORTUNA MINE.

LA FORTUNA MINE.
 In the early days of gold discovery of Califor- mia. ls4S when the news reached the gold miners of Sonora. there was general exodus of the able bodied men who were able to get away northwest to the new Fl Dorado in California. and the state of Sonora contributed many men to the mining population. They took the old road. which was known as the ''camino real, g from EStancia and Altar north westward 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 tTila range q e. went within q few feet or yards Of a very modest outcrop of quartz which one seemed tO consider of Suf. hcleut value to merit any attention. That hum. hle and insignificant quartz outcrop is today the Uutcrop of the great Fortuna mine
 IL is situated on the westward Slt DC and nearly at the base of the range of mounts ins called on some Of the old maps the Gila range. This trends northweSterly and reaches nearly to the Gila river al 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 the surfaces which however, are much pitted as if by decomposi- tion of some soft substance. But beyond these low lying hills of granite there are big outcrops Of rock which to the cxperielHed eye indicate Stratifjed formations They afe indeed strait fed, for the bulk of the range Southward and SuutheaStward is composed of regular Stratifed laminated, hard gneiSSic rock, use the word ''gneisSic' in very general and comprehensive sense, for you can describe these rocks with
 
 mica slaUcS and hornblendic states, with inter p0lationS of QuartZite beds. especially in the upper part Of the series with green stains sup 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 lurlum, which by It's decomposition has given thPSc colorS. The fact remains, however that the bullion from the upper part of tho vein con tainS more copper than ii now contains in the of rT0F7 ~1- have been carried on here have developed a condition Of things which could not be foretold from an inspection of the outcrop The vein or lode appears to be q chimney not q contino- ous ore body. nor a continuous vein with an ore body or chimney or chute upon it. As re- marked tho outcropping points indicate that this ore body.
 The vein is remarkable first in this limited out crop; second, m its continuity in depth. it's con tnuc6 satisfactory richness and the promise it gives of enrichment by further veins dipping into it on the foot-wall sides.
 Some facts in regard to the product or yield: The orc paid from the surface The product or ore extracted up to the time has been about 30 tons per day, which k sent to the 3O-Stamp mill each stamp of which cruSheS about tons in every twcnty-fOur hours. The extraction is chiefly and largely by power drills. A force of 50 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 Ia feet wide. This large space permits the use of power drills to great advantage. Tn the material hoiSted there are Fragments Of tho 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 il would take moro time and ex- penSe than II does to mill it. and there iS q chance of some or 1t containing gold From thcSe 80 tons of rock crushed daily the average Proailc: k perhaps S4s.O00 worth of gold per month. some months they have produced as high aS 390000.
 Tn the region of the Fortuna mine the forms. elons appear to be wholly of mica slate and hornblende slate, with some arenaceouS layers Ike old r1icaceouS SandStoneS and quartZiteS The mi c iH surrounded by black hornhlcndic states anu mica states, dipping southward and Southwestward at an angle of about 45 degrees and these Slates are very evenly lamnated ridge after ridge.