The Arizona sentinel., 1903-03-25
LA TORTuNA MINE.

In the carly days of gold discovery of Califor- uia is4s, when the news reached the gold miners of Sonora. there was a 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,
 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 Gila range they went within n few feet or yards of a very modest outcrOp or quartz which no one seemed to consider of sui ficient 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, or 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-lyng hills of granite there are big outcropS of rock which to the experienced eye indicate Stratified formations. They are indeed strait tied for the bulk of the range Southward and southeastward is composed of regular Stratitied, 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 localiZe them as mica SlateS and hornblendic states, with inter polations of quartzite beds. especially in the upper part of the series, with green StaTnS, 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 lurium, which by its decomposition has given these colorS. The fact remains, however, that tho bullion from the upper part of the vein con- tainS more copper than it now contains in he lower levels of the mine. The workings winch have been carried on here have developed a condition of things which could not be foretold 1 from an inspection of the outcrop. The vein or lode appears to be chimney, not contino-
 ouS ore body, nor a continuous vein with an ore body or chimney or chute upon It. As re-
 marked the outcroppng points indicate that
 there IS no very great longitudinal extension oi this ore body
 The vein is remarkable first in this limited out
 crop; second, in its continuity in depth, it's con | tinued satisfactory rich zeSS, and the promise | 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 ol ! ore extracted up to the time has been about SC tons per day, which is sent to the 20-Stamp mill each stamp of which cruSheS about tons ir every twenty-four hours. The eXtractions is chiefly and largely by power drills. A force of so men is employed by this mine and mill
 The greater part of the labor underground anG ! mining Is done by compressed air. The lode,
 was told, was to l5 feet wide. This large
 space permits the use of power drills to grea
 advantage. In the material hoisted there arc l fragments of the wall rocks, some of which art l thrown out, but many pieces pass through tht
 mill They would prefer to reject most of thi: I wall rock. but it would take more time and ex penSe than 1t does to mill 1t, and there IS 1 chance of some of 1t containing gold. From | these 80 tons of rock crushed daily the average l product Is perhaps $4S,000 worth of gold pc
 month. Some months they have produced a | high as $90,0O0
 In the region of the Fortuna mine the forma 1 tionS appear to he wholly of mica slate anC [ hornblende slate, with some arenaceous layer Ike old micaceouS Sandstones and quartzites The mine is surrounded by black hornblendi states and mica states, dipping Southward ant 1 SouthweStward at an angle of about 4o degrees
 and these states are very evenly laminated ridge after ridge.