192 B1tlletin No. 23, Washington Geologicat Survey MOUNTAIN BOY These workings·which are credited with a pToduction of several thousand dollars, are on the west side of a small ridge and about three-quarters 0£ a mile southwest of the Castle Creek camp. A part of the workings was not accessible at the time of visit and the following is quoted from a report made by Bancroft* which covers the full development of the property : " Three aclit tunnels with short drifts, inclines and other workings are located near one another on the Mountain Boy claim, about half a mile outhwest of tlle camp. The rocks explored in all these workings are a part of the limestone and shale series which prevails over a large portion of Castle Mountain and the ridges projecting from it. '' Only two of the four tunnels represent development on ore bodies, Nos. 3 and 4 llaving been driven to open ground 1mder the ore-shoots above. Tl1e No. 1 and 2 workings are within. 75 to 100 feet of one another and practically on the same level. "No. 1 tunnel is located at an clevatiou 0£ 3,920 £eet. A crosscut adit extends 30 feet, beyond which point a gentle incline 75 feet long and a steep pitch of 50 feet lead to a. level lrnow·n as No. 3. Short drifts have been run off from the main level in all directions, having 1·esllltcd from gutting the small irregular ore-bearing quartz lenses that occur along the planes of schistosity of the sedimentary rocks. Under­ grouncl ilevclopm ent shows that these quartz lenses vary in width from half au inch to 18 inches and in length along the strike from two inches to 30 feet, aud some may have greater dimensions. They contain inegularly scatterecl patches 0£ gal.ena1 sphalerite1 chalcopyrite, pyrite and tetrabeclrite. The ores show some banding and are brecciated by post-mineral movements. Both the ore bodies and the sediments are tra­ :versed by innumerable veinlets of calcite." Assays of a portion of the dump material are said to average 10 to 20 ounces of silver to the ton and during tlle winter of 1919 Mr. Cross was building a small 15-ton mill to treat a part of these dtunps. •Bancroft. Howland. The Ore Deposits of Northeastern ,vashlngton: U. S. Geo!. Survey, Bull. 550, page 207. The Metai .Mines of Washington 193 SHERIDAN DISTRICT GENERAL FEATURES Ten miles by air line northwest 0£ Republic are several properties which, after an idleness of 20 years, have been partly revived by the favorable market for silver. These are in the Sheridan (sometimes called the Cascade) District. Most of the holdings are in T. 38 N., R. 31 E., just across the Ferry County line into Okanogan County. The first location was made during 1897 and a year later the Zalia M property made the first shipment of high-grade ore. All work was suspended during 1903 and aside from an occasional shipment from th.e Phil Sheridan and Toroda mines, the district was dormant tmtil 1917. The total production has not been notably large, probably not over $100,000. The values are principally in silver with minor amounts of copper and gold. 1'he gangue minerals of quartz and cal­ cite are but sparingly present in all except the Zalla 1\1 work­ ings. Flourite is associated with the mineralization in the American Flag workjngs. The cotmtry rock in the vicinity of deposits is a medium _fine-grained igneous rock with a dark greenish cast. A thin­ section causes it to be classified as phonolite. The section examined is composed of 45 per cent soda feldspar, 10 per cent nephellite, 25 per cent aegidte and augite, and the remainder serpentine, sericite and secondary pyrite. This rock has developed a series oi narrow shear zones along which tbe ore minerals have partly replaced the phono­ lite and deposited narrow zones and lenses of high-grade ore. The deposits are usually characterized by parallel false walls which in some instances mask mineablc ore. They are not showy and constaut sampling and assaying vigilance is a necessary aid to intelligent mining. In the Zalla J\I :Mine tl1ere is a quartz vein varying in width from one to six feet aud traceable on the surface for several thousand feet. Since the greater portion of this vein is barren of values its successful development musi come from locating the workable ote-shoots. 194 Bitlletin No. 23, Washington Geological Siwvey PHIL SHERIDAN A company incorporated as the Carey Mining & Develop­ ment Company, with heacl offices in Spokane, is working the Sheridan Mine under bond and lease. It has been carrying on development work with a small crew for several years and shipments of high-grade silver ore have been made at various intervals. D uring 1918 a 50-ton concentrator was erected and since that time intermittent mill runs have tm·ned out several car loads of concentrates averaging 300 ounces of silver to the ton. The property, which comprises 10 patented claims, is owned by P. J. McCormick of Republic. During the early history of the property, Mr. McCormick is reported to have mined a considerable tonnage of shipping ore; the records of t hese shipments are not now obtainable. The mine openings are situated in a small gulch one mile north of the East Fork of 'rol'odo Creek, in Okanogan County, one mile west of the Ferry County line, and the old Sher­ idan Camp. By air line the property is nine miles nor thwest of Republic but it can best be reached over the Wauconda road, which involves a trip of approximately 20 miles. The property was visited in the absence of the operators. Both. mine and mill wer e tempor arily closed down. The pres­ ent equipment cannot furnish sufficient power for both the mine and mill. The country rock is a fine-grained phonolite. The vein fills a zone of shearing which cuts the phonolite with a strike of north 20° east and clips 50° nortlnvest. The m iner­ alized zone varies in width from one to seven feet. The hanging-wall is well de:fiuecl and exhibits a paintiJ.1g of one inch of gouge. Intense shearing along the zone has de­ veloped a series of false walls, particularly noticeable along the foot-wall of the deposit. What appears to be cleanly defined foot-wall can often be broken through and back of it at a clis­ tance of a foot or more a second or third parallel wall £oimd, identical in appearance with the first. Additional mineralization is sometimes found between these false walls. 1rhe brecciated country rock has been consjclerably altered and silicified by mineralized solutions which worked their way upward along The Metal Jll_ines of Washington 195 the shear zones. The feldspar in the brecciated rock is notice­ ably altered to kaolin and sericite while pyrite is strongly de­ veloped through the zone. The deposit appeared more in the form of a mineralized lode rather than a -vein. It is not at all showy, in fact, very little rock was seen in place that gave the appearance of commercial ore, and it is necessary to closely sample and assay in order to determine the mineable shoots. In the upper levels appreciable quantities of quartz and cal­ cite assist the ore minerals in cementing the brecciated country rock. A grab sample taken by the writer of one of the upper dumps gave an assay of 16 ounces of silver to the ton. The deposit has been opened by a series of crosscut tun­ nels driven to the vein at intervals over a distance of 500 feet up the ltillside. 'l'he lower crosscut is driven south 52° east to the mineralized zone. Drifts have been run along the zone and a limited amount of sto:ping done. An incline winze has been sunk on the vein from this level to a depth of 200 feet. This was apparently started on a well mineralized lens of ore but the mineralization does not appear to have ex­ tended all the way clown the ,vioze for little ore could be ob­ served on the walls. The upper levels are similar in plan to the adit level. They are connected by raises and several stopes have been broken. Judging from the appearance of the ground mined, the m'ineralized zone must have averaged three to :four feet in thickness. · Tlie property has a well equipped blacksmith shop and air £or the drills is furnished by a three-drill steam-driven air compressor. Description of llie Concenlrator.-'rbe construction of the mill was begun during 1918 and completed early in 1919. 4s average capacity per 24 hours is about 50 tons. 'l'he mill feed averages 15 ounces of silver to the ton and the concen­ trates 300 ounces. The machinery is operated by a agel steam engine which receives its power from a 60-horsepowcr boiler. Water for the mill comes from a storage reservo,v 500 feet down the gulch. It is lifted back to the mill tanks by a Gould three-cylinder vertical pump, operated by a six- 196 BitZletin No. 23, Washington Geological S1wvey Ore fror mine 9"x 15" Blane JClW crusher l Storage Bin J ChqHen1e Feeder Lene Mill ! f,,.ee jeffling Box Classifor . 5ar.d{ sfi~es 4 ,ter-Oy~t't!l · ~ble, ~ FIOAtir Moch. ( cncenTr-aTes Tai Is Tc111 :i C nc. 2 P~chuca Ag·1tAlion Cells in series. 5e ttlin9 Tamt Cone cur dned and TAil~ to wAste sacKd for shipment Fig.