Fern Creek Cinnabar District 1919
(Now Valley County, Idaho)
From “Tungsten, cinnabar, manganese, molybdenum, and tin deposits of Idaho”
University Of Idaho School Of Mines Bulletin No. 2
Moscow, Idaho Jan. 1919
By D. C. Livingston
With Notes on the Antimony Deposits By Francis A. Thomson
Cornell University Library TN 24.I2L78 Chapter III page 55-65
Field Work and Acknowledgments, Etc. The Fern Creek district was visited by the writer early in August, 1918. It was understood in the spring that Mr. F. L. Ransome, of the U. S. Geological Survey, would visit this district and it was the intention to endeavor to make the examination jointly with him if this could be arranged. Mr. Ransome did not come west and the director of the Survey was unable to give any definite information as to when a representative would visit the district, so the writer decided that as the district ought to be examined and reported upon, the trip was made independently of the Geological Survey. Mr. E. S. Larsen, of the Survey, visited the district several weeks after the writer which unfortunately caused duplication that might have been avoided.
Ten days were spent altogether on the trip after leaving Cascade, five of which were spent in traveling and five in the district. Of these five days, two were spent in examining the different prospects and workings and the other three in the construction of a geological map in the vicinity of the Fern mine.
Acknowledgments are due to Mr. Walter Hovey Hill for the claim map of the district and also for the excellent detailed map of the workings and geology of the Fern mine. Acknowledgments are also due to the various operators of the district for their assistance, and particularly to Mr. E. H. VanMeter for personal courtesies and invaluable assistance to the writer during his stay in the [district.]
Location and Roads. This district is situated in Valley County in unsurveyed territory in what is almost the geographical center of Idaho It is in the Yellow Pine mining district and about seven miles from the once prosperous but now water-covered town of Roosevelt, the former metropolis of the once celebrated Thunder Mountain gold camp.
It is reached from Cascade, the county seat of Valley County, which is on the Long Valley branch of the Oregon Short Line. A wagon-road extends from Cascade to the district, a distance of about 70 miles. This road was built during the Thunder Mountain boom, some 15 or 16 years ago, and since that time has had little work done on it, so on the whole it is in a bad condition. An automobile in good running order can go as far as Knox, which is about 26 miles, but beyond that point it is not practicable for cars on account of high centers, sharp rocks and excessive grades. Between the railroad and the mines in the Cinnabar district four summits have to be crossed; the following figures give the elevations along the road at different places, taken with a barometer going in and checked coming out. The distances are only approximate.
After Reardon Creek summit is reached the road follows the high ridge forming the divide between the South Fork and Middle Fork of the Salmon River, which is evidently a remnant of the original plateau from which, according to Umpleby the central mountain region of Idaho was carved.
The road is rough but interesting, both from a scenic and geological point of view. Soon after leaving Cascade glacial morainal deposits are encountered containing many large granite boulders. The country lying between the North Fork of the Payette River and Johnson Creek was evidently ice-covered in the glacial period, with ice tongues extending well down into the valleys, and is part of a region which was evidently covered by a local glacier of considerable area. The center of this glacier appears to have been somewhere in the rugged granite mountains that form the divide between the North Fork of the Payette River and the South Fork of Salmon River.
Morainal deposits extend down to Long Valley from this glacier, as well defined drumlins (gravel ridges deposited by glaciers) extend some distance into the east side of the valley a few miles south of Payette Lake, and this lake itself has been formed by the blocking of the valley with morainal material. Upper Payette Lake has also been formed by the damming of the North Fork of the Payette River by a moraine from the mountains to the east. This glacier evidently also covered the rugged mountain area lying between Payette Lake and the Little Salmon. It did not extend as far north as the Salmon River as there is no evidence of glaciation in the Warren district. Small local glaciers of the alpine type existed in all the higher mountains of Central Idaho, the Fern Creek camp itself being located in an old glacial cirque, but this particular area seems to have been covered by ice of considerable extent and thickness. It is interesting to note that this is a region of heavy snowfall at the present time, which might be a possible clue to the glacial conditions in the past. This region offers an interesting field for study in local glaciation and it is hoped that at some future time it may be more thoroughly investigated.
It is difficult to see how the grades on the present road could be much improved without spending nearly as much money as a new road would cost. The grade over Cabin Creek summit could be lessened by some more switch-backs on the Cabin Creek side, thereby lengthening the distance to the summit, and the same is true on the other side though the grade here is not excessive. The grade from Johnson Creek to Trapper Flats could have been lessened by striking Trapper Creek lower down, as considerable grade is lost by rising too high and then coming down hill to the crossing of Trapper Creek. This would be very expensive and would entail rebuilding several miles of road. The worst grade on the road is from Trapper Creek summit down to the crossing of Reardon Creek and except for the avoidance of rock-work seems to be entirely unnecessary. Parts of this grade are in excess of 20 per cent, and it is a physical impossibility for a team to haul much more than an empty wagon up this hill. The grade from Reardon Creek to the Reardon Creek summit is bad but not so steep as on the other side of Reardon Creek and as mentioned above, both these could have been practically eliminated by crossing Reardon Creek a mile or so further up.
It is unfortunate that this new cinnabar camp is handicapped with such a road, for though the country is mountainous and rugged, it would have cost but little more in the first place to have built a road with no grade exceeding 10 to 12 per cent if it had been put in the right place to begin with, whereas now, there, are many places on the road where the grade exceeds 20 per cent and some probably as high as 25 per cent.
Most of the freighting is done by the day and there were no teams hauling by contract, but the cost of freight to the camps, figured from the time necessary to make a round trip, is in the neighborhood of $100 per ton, or 5 cents per pound.
History. Cinnabar float was discovered in Cinnabar Creek, a tributary of the East Fork of the South Fork of Salmon River, during the Thunder Mountain boom in 1902 by Pringle Smith.
Mr. Smith discovered the vein from which this float came and located three claims known as the Hermes group, upon which he has faithfully performed his annual assessment work ever since. After the Thunder Mountain excitement died down the district was deserted and until 1917 Mr. Smith was for many years the only prospector or resident in this inaccessible and lonely region, except for an occasional sheep-herder.
In 1917 Mr. E. H. Van Meter, a well-known mining man of Central Idaho, and a former partner of Mr. Smith, located the Fern group of claims on the other side of the ridge from the Hermes group and adjoining these claims. He erected a small retorting furnace and began extracting quicksilver. His success resulted in a number of men coming into the district and locating ground, particularly in the spring of 1918. Although there are many legitimate locations among the more recently staked claims, the majority are entirely worthless- and were staked with the sole intention of holding ground which somebody else’s work might make valuable, a mineral discovery being entirely a secondary matter. The result has been detrimental to the district, as several experienced prospectors who came in during the summer of 1918 turned back in disgust when they found the whole country covered with locations, many of which were made in the snow.
In the summer of 1918 the following claims were being operated: The Fern group, by Mr. Van Meter; The Hermes group, bonded from Mr. Pringle Smith, was being worked by Mr. Oberbillig, of Boise; The Buckbed group, owned by the Marks Bros, and associates of Boise, was being worked by Mr. Ray Call, and the White Metal group adjoining the Buckbed, was being worked by Mr. George C. Brewer.
With the exception of the Hermes group all of these properties are located on the east side of a high ridge separating the heads of Fern and Cinnabar Creeks, both of which are tributaries of the East Fork of South Fork of Salmon River. The buildings of the Fern property occupy a glacial cirque, or basin, at the head of Fern Creek. Topography. The Fern Creek camp is situated close to the divide between the South Fork and the Middle Fork of the Salmon River. This divide has an average elevation of between 8000 and 8500 ft. with occasional points or mountains upon it with elevations up to 9000 ft. or more. Nearly all the claims in the district lie upon the South Fork side of the divide. The topography is very similar to that which prevails all over Central Idaho and consists of steep sided canyons separated by high ridges, some of which are flat topped, showing the present shape of the country to have been derived from the elevation and subsequent erosion of a rolling plateau.
This high region was occupied by local glaciers during the Pleistocene or Glacial period. These glaciers did not apparently cover the whole of the region, as they must have done further to the west, but consisted of small disconnected alpine glaciers along the high ridges. These glaciers have formed many cirques or circular amphitheater-like depressions at the heads of the creeks.
The creek valleys below these cirques are U-shaped and the floors of the valleys are covered with glacial wash.
Geology. Rocks of the District. The district is underlain by a series of steeply tilted and highly metamorphosed sediments consisting of quartzites, limestones and schists, intruded locally by quartz porphyry dikes and also by outliers of the great granite batholith of Central Idaho.
The age of these metamorphics is uncertain as no definite fossils were noted. Certain crushed and deformed white objects in the crystalline limestone may possibly be crinoid stems, but this is extremely doubtful. The metamorphics are older than the Cretaceous period, as they are intruded by granite of that age, and are probably of the same age i. e. (Lower Paleozoic) as the sediments at Gilmore and other parts of Lemhi and Custer counties, but this is merely a supposition.
The outcrops are best seen on the ridges along the heads of the old glacial cirques. The depressions occupied by the streams are filled in many cases with glacial debris and the outcrops are somewhat meager. Map No. 5 gives, in a general way, the topography and geology covering about four square miles and shows the main geologic relations. It makes no pretense of extreme accuracy, as it was made in less than three days by means of a pacing and compass survey with a traverse board, using a barometric base for the elevations.
The claim maps and map of the Fern Creek workings were made by Mr. Walter Hovey Hill, of Boise, a Mineral Surveyor and mining engineer, who spent several weeks in the district surveying claims for patent, and are consequently accurate maps.
In mapping the geology the ridge between Sugar Creek and Fern Creek was followed and also the ridge between Sugar Creek and the East Fork of the South Fork of Salmon River. On both these ridges the same sequence of formations was found, and the same sequence has been mapped as occurring in the intervening- lower ground, though this is largely covered with morainal material.
Taking these formations in order from the north to south, they consist first of a purplish to gray shaly limestone, which outcrops on the ridge northwest of the Hermes group and is also found in the workings of those claims. It occurs in narrow bands or beds with well marked bedding-planes and its .thickness is not known.
Next to this is a massive crystalline quartzite, sugary in appearance and varying in color from white to almost black in places. It is heavily iron stained and being very hard and less easily weathered than the other rocks of the district, has remained in the form of steep bluffs along the cirque walls. It contains small gash veins of quartz in places, many of which were staked in the Thunder Mountain boom. It has a thickness of about 2000 ft.
South of this is a micaceous schist containing bands of green hornblende, which gradually grades, in going south, into a limey slate of purplish color with hard cherty bands. This slate is considerably contorted, the bands being crumpled into a complexity of folds. Its thickness is from 700 to 800 ft.
Next to this comes a yellowish and highly crystalline soft limestone, which weathers and disintegrates into a yellowish sandy soil, giving more easy slopes to the mountain side. This contains in places some crushed and flattened white objects that may be crinoid stems. The cinnabar ore of the Fern and adjacent properties occurs in this limestone. Between this and the slates lies a bed or sill of almost pure tremolite, or white fibrous hornblende, with an average width of 10 ft., and apparently very persistent, as it outcrops on both ridges and also between the ridges at the head of Cinnabar Creek. The thickness of the yellow limestone is about 500 ft.
South of the limestone is a massive quartzite conglomerate with quartz pebbles up to 2 or 3 in. long. This grades into a massive gray crystalline quartzite and further to the south the conglomerate again shows with a total thickness or outcrop width of from 2500 to 3000 ft.
South of this the same soft yellowish limestone as appears at the Fern property comes to the surface. It is somewhat shaley in places, but is undoubtedly the same rock. Time did not permit further exploration to the south to see if any of the other formations were repeated, but the indications point to an eroded fold with the quartzite and conglomerate probably the lowest members of the series.
The igneous rocks in the area embraced by the map are not quantitatively important and occur in only a few places. Further to the east the country rock is made up largely of certain effusives of different kinds, many of them in layers, or flows, one of the best examples of which is Rainbow Peak, which derives its name from the red and yellowish bands of igneous rock of which the mountain is made up. To the west the big granite batholith comes to the surface, and the particular area in which the cinnabar occurs lies between these two, and is either an uneroded remnant of metamorphosed sediments or else a part of the sediments that escaped the lava flows of the Tertiary period. It is undoubtedly underlain by the granite at no very great depth. In the southwestern part of the area a tongue of granite intrudes the yellow limestone. It is identical with the granite found elsewhere in Idaho and described in other publications and is a high point or outlier of the big mass of this rock to the west.
In the neighborhood of the Fern mine several dikes of quartz porphyry occur. A similar rock is seen in the Hermes group to the north, one of these dikes being cut by the middle tunnel on this property. This tunnel passes through 16 ft. of porphyry which is very much decomposed and appears to be in the form of a sill with blue lime on the footwall and yellow crystalline lime on the hangingwall side.
A dark, fine-grained basic dike rock is seen on the trail between the Hermes group and the Fern mine. This same rock can also be seen on the ridge west of this trail and is probably continuous for some distance below the morainal material piled up at the mouths of the cirques.
The most important of these igneous rocks would seem to be the quartz porphyry, as it is an accompaniment, wherever it occurs, of the cinnabar mineralization. This, of course, may be merely a coincidence, but it is difficult to recognize it as such, and indications point to the suggestion that the solution that brought in the cinnabar had their origin in the same volcanic source as that which formed these dikes.
Fern Mine. This is situated at the head of Fern Creek in a glacial amphitheater. Cinnabar occurs in chalcedonic quartz seams in the soft, yellowish limestone already described. These seams vary in width from a few inches up to 3 or 4 ft. Several of these seams outcrop over a width of about 50 ft., most of them containing cinnabar ore of good grade. These cinnabar seams or veins are irregular in their occurrence and are evidently replacements of the limestone by mineral-bearing solutions. Although irregular in size, they seem to be fairly persistent where followed along their strike, as one of them has been followed for a distance of about 80 ft. by a tunnel and showed 2 ft. of ore in the face that contained 3.8 per cent of mercury.
The general strike of these seams on the Fern property is about N. 35° E. with a dip to the northwest. This strike is almost at right angles to the general strike of the metamorphic beds. The mineralization of these deposits is very simple as cinnabar is the only sulphide mineral present and the gangue is a chalcedonic quartz full of vugholes and containing in some cases a reddish chert or jasper. “The limestone in the neighborhood of the cinnabar veins is full of solution cavities and these deposits probably occupy what were formerly solution cavities in this easily replaceable rock.
At the present time there is no great quantity of cinnabar ore in sight as the workings consist only of two tunnels about 80 ft. apart and not over 100 ft. long and some open cuts and quarry holes that follow the cinnabar bearing seams into the hillside.
Considering the small amount of work that has been done the showing is good, as there are at least five of these irregular seams occurring over a width of 50 ft. and most of these show ore running from 3 to 8 per cent in mercury.
About five tons of ore that would average 5 to 6 per cent of mercury, was being extracted daily to supply the small retorting furnace. This ore was being obtained from development work and not from stoping.
These deposits occur only a short distance (not more than 200 ft.) from the contact with the quartzite conglomerate and it is possible that underground exploration towards this contact might discover other replacement-seams as the impervious nature of the quartzite would undoubtedly cause a damming back of solutions thus making a likely place to find ore.
Hermes Group. This group is situated about a mile north of the Fern mine and has several hundred feet of workings in the form of tunnels on the property.
A heavily iron-stained zone outcrops on the hill north of Cinnabar Creek, in the bluish lime previously mentioned. This iron-stained outcrop consists of shattered lime and some bluish quartz and contains disseminated cinnabar all through it. It is 50 to 60 ft. wide and in one place is harder than the surrounding country rock and makes a bold and prominent exposure. Some large boulders of float have rolled down the mountain from this outcrop. One of them larger than a railroad box car contains a considerable amount of finely disseminated cinnabar. This mineralized zone occurs in the lime a short distance from the dense, iron-stained quartzite previously mentioned.
This hard mineralized zone does not seem to extend far down the mountain, but the cinnabar mineralization is found almost as far down as Cinnabar Creek, and has been opened up by three tunnels.
The lowest of the tunnels follows a shattered mineralized zone, which appears to be along a contact between the quartzite and the lime. At the mouth of this tunnel there is exposed in an open-cut about four feet of cinnabar ore which gave an assay of 3.22 per cent of mercury. The tunnel is about 135 ft. long and runs N. 35° W. (magnetic) which is the general direction or strike of the metamorphosed sediments. The shattered limestone in this tunnel shows a little cinnabar, a sample giving a return of 0.20 per cent of mercury.
The middle tunnel is 80 ft. long and has a course of N. 10° E., so it partly crosses the mineral formation. The first 50 ft. is in blue lime carrying a little cinnabar. It then passes through a rotten porphyry dike or sill 16 ft. wide and the face is in hard, yellow crystalline limestone with a strike of N. 60° W. and a southwest dip of 80°.
The upper tunnel is mostly in unmineralized limestone, it appears to have reached the mineralized zone in the face, but no very definite information can be obtained from this tunnel.
A somewhat hasty examination of the property seems to establish the occurrence of a wide belt of shattered mineralized limestone, somewhat hardened by silicification in places and also heavily ironstained, running in a northwest direction close to a contact with a hard, dense iron-stained quartzite. Cinnabar occurs all along and through this zone for a distance of at least 600 ft., and possibly further.
Most of the cinnabar is too finely disseminated to be classed as ore, but there are local concentrations of higher grade material which can undoubtedly be worked at a profit, and there seems no reason why development along this zone should not open up considerable cinnabar ore of workable grade.
The deposits of the Fern and Hermes groups are similar in the fact that both occur in limestone close to a contact with a more impervious rock which is quartzite, and are both associated with the same kind of porphyry dikes.
Their origin is undoubtedly similar and is probably to be explained by heated waters, similar to certain kinds of hot springs now in existence, which deposited the mercury minerals and cherty quartz either by replacement of the limestone or by filling of solution cavities along fracture planes.
The porphyry dikes are probably connected with a deeper seated mass which supplied the heat to the waters forming the veins and possibly furnished the minerals. The explanation for the cinnabar mineralization close to the quartzite contact is possibly that this rock being more impervious to water than the adjoining limestones would interfere with the underground flow of water in the latter, damming back the solutions and thereby giving more chance for chemical interaction and precipitation. It is a well known fact that ore shoots or bonanzas in gold and other mineral veins often occur near faults and this is explained by the gouge of the fault plane acting as a barrier to the water in the manner just described, and thereby causing enrichment of the vein at that point. Cinnabar is widely distributed in this district, but other workable deposits of it will most likely be found in the limestone near some such impervious barrier as a contact, a dike or a fault.
The Buckbed Property is situated about 1000 ft. to the east of the Fern mine and in the same belt of lime.
There are several open cuts which show the same character of chalcedonic quartz replacements in the lime as at the Fern, running about north and south. One of these shows some fairly good cinnabar ore, but not enough work has been done upon it to prove the value of the property, though its general appearance is encouraging. A good camp has been built with substantial houses designed to withstand the deep snows of this region in winter time. A tunnel has been started near the lowest end of the claim and within a short distance of the camp. This tunnel will tap the cinnabar bearing vein about 150 ft. below the surface and should show some interesting developments. The camp has been built close enough to the mouth of this tunnel so that the latter can be reached by a covered path from the cabin.
The White Metal Group is owned by the Idaho Quicksilver Mines Co., of Boise, Idaho, and operated by George C. Brewer.
They join the Buckbed claims and the same geological conditions prevail as on that property. A gray chalcedonic quartz replacement-vein 4 or 5 ft. wide containing jasper and cinnabar and with a strike of N. 30° W. has been traced for several hundred feet and exposed by open cuts. The lowest of these open cuts show a little copper carbonate as well as a little cinnabar, and some cinnabar is also to be seen in the open cuts higher up the mountain.
The same company owns a claim about half a mile further down Fern Creek, where some ore containing galena, stained with copper carbonate and containing a little cinnabar, has been exposed by a small open cut in limestone, on the west bank of Fern Creek. The extent of this exposure is not known as the open cut was partly caved, but the prospect would seem to be worthy of further development.
H. T. Abstein’ s Property lies to the east of the White Metal group and not far from the divide between Fern Creek and Monumental Creek. The country rock is the same yellowish lime and exposed a similar type of deposit to those which occur on the properties just described. Some excellent cinnabar float has been found by Mr. Abstein on this ground, though the vein from which it came had not been uncovered at the time of the writer’s visit to the property, though Mr. Abstein reported later that he had found this vein and that it contained good ore.
The Hennessy Property is situated in one of the cirque walls at the head of Cinnabar Creek and about half a mile south of the Hermes group. The country rock is the yellowish limestone, of the same belt as that in which the Fern and other properties occur, but further to the northwest. A vein occurs in the lime with a strike of N. 45 to 50° W. and a dip of 50° to the northeast. This vein consists of a shattered quartz and lime gangue and contains a little cinnabar. It is probably a bed or blanket vein as it had the same general course as the stratified rocks of the district. A small quartz vein from 1 to 6 in. wide and running due north and south (magnetic) intersects the larger vein and an incline shaft has been sunk at the junction of these two veins. The dump shows considerable stibnite with small specks of cinnabar. This stibnite streak must have come from the small vein and does not appear to be more than 3 or 4 in. wide at the most.
Summary and Conclusion
No very definite statement as to the probable future of the camp can be made in the present state of its development. The total amount of development work at the time of writing does not aggregate much over 1000 ft. The general indications from the work that has been done, however, are very encouraging and there seems no reason why this district should not be a producer of quicksilver to no small amount when more fully developed. The nature of the ore occurrences at the Fern and adjoining properties i. e. replacement veins in limestone, is such that the continuity of any one of these for any distance is extremely doubtful, but providing there are enough of them, as there seem to be, this fact should be no great detriment.
At the Hermes group, on the other hand, there seems to be a larger and more continuous body of disseminated cinnabar which requires considerable development to properly exploit, but this may prove of greater value than the richer but more uncertain deposits on the other side of the ridge. The remoteness of the region and its high altitude are its greatest drawbacks, and gold, silver and mercury are about the only metals that could possibly be mined at a profit under such adverse conditions. The greatest need at this time is a better road as the present one is a disgrace and only fit to drive sheep over, and if the transportation was improved there is little doubt that the district would go ahead and prove a valuable asset to the mining resources of the state.
source: “Tungsten, cinnabar, manganese, molybdenum, and tin deposits of Idaho” by Livingston, D. C. (Douglas Clermont), 1877-; Thompson, Francis A. (Francis Andrew), 1879-, Publication date 1919
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Evening Capital News. (Boise, Idaho), 26 Feb. 1919.
source: Chronicling America: Historic American Newspapers. Lib. of Congress.
page updated Dec10, 2020