Pearl Mining District, Once Abandoned, Now Booming
Boise Capital News, Boise, Idaho, Saturday, August 31, 1935
By ROBERT N. BELL
Former Idaho Inspector of Mines
One of the most convenient districts in which to look for a small gold mine that might be built up into a profit making unit of $10,000 to $100,000 a year, for initial capital risks of similar amounts, is the Pearl district, situated 20 miles north of Boise and 4 miles from the main North-South highway, over a poor spur road on light grades to the center of the camp.
The original ore discovery of the Pearl district was made in the '70's by the early day placer miners who, however, did not find anything to justify more than a few scattered prospect cuts in rather lean ore. In 1894 the camp consisted of one cabin under a grove cottonwood trees, occupied by cowboys as summer cattle range headquarters. During that year, a section boss by the name of Dan Levan wandered into camp with a wife and two or three small children, looking for a summer camping place. He had been discharged from his job on the Short Line for some infraction of the rules and the cowboys taking kindly to him encouraged his settling there, pointing out to him some rusty streaks on the side hill where they had found some good gold pannings in which they were not interested for themselves but which they thought might make a living for him.
Dan Levan took to prospecting; ran a cut on the discovery shown him; found rich ore from which he could makes wages with a hand mortar; soon expanded his operations to a horse arrastra, the cowboys supplying the horse power, and commenced to make money. When the cowboys returned the following spring, Levan had gone highbrow, built a fence around his camp and put up a sign—"D. Levan Mine. Keep Out." The cowboys were offended and recognizing that his locations were poorly made, jumped the ground and a lawsuit resulted. This, the first mining title suit in the Pearl district was settled by a prominent young Boise attorney of that day who found a purchaser for the property and settled the case out of court by dividing the spoils equally to the satisfaction of all concerned. The purchaser was a bonanza king of that day—Colonel E. H. Dewey—then enjoying the flush production of the rich ores of the Trade Dollar Consolidated. The young Boise attorney who handled this settlement and has for the past thirty years unselfishly given his great talent to the settlement of affairs, state, national and international, and to the zealous support of the great American Magna Charta was William Edgar Borah.
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The Pearl district is situated on the extreme southwestern spur of the Idaho granite batholith at the point on the Boise mountains between the Boise and Payette rivers where the granite terminates in the adjoining vast accumulation of lake bed sediments.
The surface of the district is deeply soil covered and the veins and formations largely blind. The extensive vein system of the district consists of a series of sheared fissures in the granite or in contact with dacite and rhyolite dikes. Quartz is not conspicuous in the veins which consist essen-tially of replacement deposits in sheared gangue with the strong development of kaolin and clayey gouge. The shallow ore is brown and oxidized, iron stained vein gangue with occasional ribbons of quartz in the surface conditions of the principal mines. This oxidized ore has proven very rich in free gold at several of the properties but the oxidation rarely ex-tends over 50 feet below the out-crop when the primary ore comes in consisting of pay streaks up to a foot in width of massive iron sulphide well sprinkled with galena and zinc blende with occasionally a little copper minerals. This primary ore is very distinct and readily recognized when encountered. The ore bodies in several instances have proven very persistent in strike length and to a depth of 600 feet. The values encountered in the primary ore have ranged around a quarter to half an ounce gold per ton with occasional seg-regations of much higher values. This sulphide ore proved difficult to treat by the poor metallurgical methods employed, as extraction of 20 per cent to 30 per cent of the values by amalgamation were about the best results obtained by any of the old milling methods. The ore is friable and the sulphide minerals readily separated. The treatment was largely by amalgamation and gravity table concentration, the concentrates shipped to the Salt Lake valley smelters.
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The principal producers of the district have been the Checkmate, Lincoln, Leviathan, Friday and Black Pearl mines. The total production of the district to date has exceeded a million dollars in value.
I am indebted for the early history of the district to J. C. Johnson, better known as Checkmate Johnson, who was one of its first operators. Mr. Johnson was a hard rock miner from Colorado who came to Boise in 1894 and was attracted by the reports of new discoveries at Pearl. He got a Salt Lake promoter by the name of Chapin interested in the Checkmate which had just been located and had some 10-foot prospect holes on it; got an option on the property for six months at $6000 upon a cash payment of $1000. Chapin interested a party of Oregon Short Line officials in the deal and put Johnson in charge of the enterprise. He started trenching the vein on a 6-inch pay streak from which, within the life of the short option, he extracted and shipped 20 carloads of gold ore that gave net smelter returns of $100 to $150 gold per ton. This early production paid for and financed the further development of the mine.
The ore turned base within 50 feet of the surface. It was developed subsequently by a two-compartment vertical shaft 600 feet deep and equipped with a 10-stamp mill. After a total production of half a million dollars, a strike fault interrupted the vein course at the 500-foot level; a fire destroyed the mill; the enterprise failed; the property was sold for a song and except for two or three minor attempts to re-open it, the property has since remained idle.
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The Lincoln mine, a mile farther west, was originally developed through an incline two-compartment shaft on the vein by a prominent eastern patent medicine man. This development was subsequently carried through a vertical shaft to the 540-foot level. At the 300-foot level the typically sheared ore body was 1200 feet long and stoped for that length in widths varying from a foot to a maximum of 30 feet with average values of about $12 per ton below the shallow oxidized horizon.
The biggest swell in the vein, known as the Log Cabin shoot, about 700 feet east of the shaft, was 30 feet wide and carried bands of massive sulphide ore up to a foot thick and a network of stringers throughout its full width. Sev-eral cars of crude ore were shipped from this stope that yielded $90 per ton gold.
An attempt to stope it with square sets without filling caused a collapse of the stope before it was up four sets and this splendid ore showing was lost and I think still remains largely intact. After a production of half a million dollars by this company the property changed hands and has since had several owners. The last attempt to re-open it was about 1928-29 when a lot of good capital was ruthlessly wasted in surface improvements, grass root developments and wandering away from the vein at the 540-foot level.
This is one of the strongest and most persistent gold ore shoots in Idaho. It strikes nearly east and west, dips about 60 degrees to the north and lies in contact with a big dacite dike hanging wall. This formation makes persistent swelling ground in which drift timbers commenced to take pressure and cause trouble three months after they were put in place. These operators would not be advised to run their development in the granite footwall to avoid this swelling ground and were in constant trouble from a condition that could have been avoided with intelligent management.
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The Leviathan, an eastern extension of the Checkmate vein system, carries a strong sheared fissure vein in the granite and also one of the long ore shoots of the district that was stoped at a shallow adit tunnel dept a few hundred feet below the surface for a strike length of 500 or 600 feet in $10 to $15 values with segregations of massive sulphide high grade, from which a number of carload shipments were made that ran $50 to $100 per ton.
The continuation of this ore shoot the Black Pearl mine was quite extensively developed but proved base and unprofitable in spite of some quite elaborate mill-ing attempts.
SOME UNUSUAL ORE
Adjoining this property to the south on the same parallel system of fissures of which there are a number in a 2000-foot cross-section, the Friday mine was developed 200 feet deep; had a pay shoot 1 to 3 feet wide and 150 feet long, that was richer in lead then the other ores of the district. Its production in crude ore included a number of carload shipments of 20 per cent to 40 per cent lead and $50 to $100 in gold and silver values. A 300-pound specimen of this ore shown at an Idaho state fair in Boise of nearly clean galena exhibited coarse visible gold in the galena crystals—a rather unusual occurence.
Except for the Lincoln mine operations in 1928-29, the camp has been practically deserted for the past twenty years. About two years ago Mr. J. B. McKinney, an experienced Nevada who had worked at the Lincoln and found himself out of a job, nosed around the original Levan discovery where in cleaning out some of the old shallow surface cuts he found some of the early day rich oxidized ore, and followed Levan's start, made wages pounding up the ore in a hand mortar.
The owner of this property, due to the experience of other operators in the district and the refractory character of the ore compared to what he was used to handling at Silver City had patented the ground and forgotten it. Mr. McKinney obtained a lease and option from the heirs and continued his investigations.
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FISSURES PARALLEL
The Levan fissures parallel the Checkmate at a distance of about 1000 feet on the opposite side of Willow creek. The vein had four shallow trench openings at intervals of 1000 feet for a strike length of 4000 feet. In the central opening, Mr. McKinney has since demonstrated the existence of an ore shoot, 60 feet long, with two inches to a foot of high grade oxidized ore and in addition several feet of good milling values. He is en experienced and careful judge of such matters and has made a handsome living in following up this work at this and other points along the course of this persistent fissure. He installed a baby Ellis mill and extracted several ton lots treated by this little plant that yielded $125 to $450 per ton in free gold.
He now has an incline shaft 90 feet deep which exhibits the same small rich pay streaks and several feet of good milling values. This has just been intercepted 200 feet deeper by a crosscut adit tunnel, now 500 feet long. This deVelopment will be continued until a year's ore supply is assured which seems quite definitely in prospect, when the property will be equipped with a 25-ton capacity mill, for which ground preparations and water supply have already been prepared. It seems likely on such a persistent fissure another Pearl producer is now in the making on a conservatively and intelligently handled line of attack.
SOME RICH SILVER
A mile north of Levan's mine, another strong parallel fissure under the crest of Crown Point, one of the highest weathered summits of the district, on the divide between Willow creek and Payette river, is of the bi-metallic variety and contains as much silver as gold with some segregations of rich silver mineral. This property, known as the Florence, was developed a number of years ago with a short crosscut tunnel and an incline shaft with considerable drifting and made crude ore shipments to the Salt Lake smelters of 20 to 60 ounces silver ore. This deposit has been idle and inaccessible for several years.
Another old prospect, abandoned 30 years ago, an eastern extension of this vein system, known as the Apache, was developed with an incline shaft to a depth of 150 feet and was reputed to have opened some rich segregations of both silver and gold values. A year ago this property was taken hold of by a bunch of college boys who ran a crosscut tunnel to tap these old workings and hit the shaft accurately with a 250-foot drift but a little too high to bottom it and had no means of taking the water out and finding what the development disclosed. However, at a distance of 50 feet in from the portal of this crosscut they encountered a blind vein which was 2 to 4 feet wide containing good values. A drift was extended on this fissure a short distance and from this shallow grass root work 100 tons of ore was accumulated at the portal of the tunnel which is now in evidence and is said to give an average value of $12 per ton in gold, several ounces of silver and some occasional strong showings of galena and lead carbonate—a most attractive exhibit for further development and an illustration of the interesting opportunities the district affords.
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EXTENDS BEYOND RIVER
One of the most promising prospects of the district for development is on the Middleman group, lying east and south of the Friday, Leviathan and Black Pearl mines, as the underground development of these properties demonstrated that the strong showings of several fissures extended into this property and in one instance was proven beyond the common boundary lines.
The extensive fissure and dike system of the Pearl district extends north to and beyond the Payette river in the vicinity of the Idaho Power company's small power plant. In this locality the Osborne, the Nellie Bly and two other mines were extensively developed by short and long cross-cut tunnels on the strong fissure veins in the granite and igneous dike contacts in the characteristic ore of the Pearl district but lower grade in gold. Three of these properties had crosscut tunnels fully 1000 feet long. The values of around $4 to $6 proved too low grade for profitable operations on several small milling attempts but at the new price of gold might justify re-opening. 'Most of these old works are caved and inaccesible.
WOULD JUSTIFY TESTS
On the opposite side of the river, half a mile north of the power plant, the Jumbo mine is a great shear zone in granite and associated dike rocks, 200 feet wide. It carries a wall band 20 feet wide of $4 gold ore and scattered low grade values across its full width, This property has 500 feet of adit tunnel work, surface pits and shallow shafts. The bulk of the deposit probably would not run $1 per ton but as it carries considerable manganese oxide there may have been some surface leaching of its gold values, as in the shallow shafts across its width, pebbles of primary sulphide ore including chalcoprite are found that give gold values up to $9 per ton, and the deposit seems to justify a diamond drill test with a view to disclosing sufficient average values to justify a mass production operation.
East of the Pearl district and separated by only a narrow belt of lake bed sediments in the erosion trench followed by the state highway, a short distance above Horseshoe bend on Shaffer creek, a most interesting area of mineralization occurs in the granite associated with immense rhyolite porphyry dikes where the Ackley, Brogan, Earlywine and Cox prospects have considerable shallow development on broad mineralized shear zones containing narrow pay stringers of quartz showing occasion specimens of visible gold. These big zones are from 100 to 200 feet wide and according to their owners carry average values of $2 to $6 per ton. These deposits are under examination and extensive sampling at this time by one of the prominent northwest mining organizations with a view to a thorough diamond drill test in the event the shallow values encountered prove sufficiently attractive.
STUDIED BY GEOLOGISTS
The geology of the Pearl district was studied by Waldemar Lindgren and his findings published in the 18th annual report of the U. S. geological survey in 1895. One of the most timely and interesting studies of the district was made last year by Dr. Alfred L. Anderson of the state bureau of mines and geology and his results published in pamphlet No. 41. It is a pity the state department is not better supported in this line of foundation work for the creation of new wealth in the form of a much needed sound money supply.
(To Be Continued)
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