Synopsis of a Report on Mining in Calfornia and Nevada, U.S.A

Introduction

. The Californian scheme, as it has been termed, originated with the well known mining capitalist, Geo. Lansell, Esq., of Sandhurst, shortly after his return from a tour through Europe aud America. Whilst sojourning in the State of California, Mr. Lansell, who, it is needless to say, possesses a very extensive practical mining knowledge, observed many instances connected with mining and the treatment of auriferous ores, which were there very successfully worked, and which, if introduced here, would, in his opinion, result to the advantage of our miners on Bendigo or elsewhere. Having come to this conclusion, Mr. Lansell, on the 12th November 1876, commu nicated with the committee of the Bendigo School of Mines in furtherance of that view, and at the same time very generously offered one-third (on certain conditions) of the total expense it would take to send a qualified delegate to America.

The committee referred to took immediate steps to raise a sufficient amount by means of subscriptions from the citizens of the Sandhurst district, aud applications were requested in the newspapers from persons competent and willing to proceed to the Pacific slopes. Out of nineteen applicants — the necessary funds having meanwhile been subscribed — two were selected, and these two candidates were sent as a final test to the Clunes and Stawell mining districts for the purpose of examining and reporting on the mines there, in the same way as the chosen delegate would have to do in California and Nevada. On the 12th February 1877, the author of this present synopsis of his report was appointed, and on the 5th March following he left Melbourne, en route for San Francisco, California. The delegate was furnished with a precis comprising the heads of subjects on which the investigations were to be made and reported upon after his return to Australia ; besides, letters of introduction were procured for him from the Chief Secretary (Sir James McCulloch, K.C.M.G.), to their Excellen cies the Governors of the States of California and of Nevada, in order to afford the delegate that standing and aid to which he, as the representative of the metropolitan quartz mining district in the colony, should be entitled.

A similar communication was handed him for presentation to the (late) MINING IN CALIFOENIA AND NEVADA. American Consul-General in Melbourne, Thos. Adamson, Esq., jun., who, as a fellow-passenger to California, introduced the delegate to all the leading mining and professional experts in San Francisco, thus paving the way for success fully carrying out his mission, and for which services he desires to record his thanks. Amongst the numerous gentlemen in hoth the States visited, who received the delegate so very kindly and hospitably, and who aided him so disinterestedly in his laborious task, the proprietor of the Alta California, Fredk. MacCrellish, Esq., deserves special mention, for his rendering, besides, timely and unsought-for aid when the delegate was unfortunately left, for a considerable period, in an embarrassed position through non-arrival of remittances.

The return to Victoria was accomplished after an absence of nearly five months, of which time two months were passed on the sea, leaving a very short time for his investigations at the mines of the Pacific slopes and Nevada. The original report was handed to the committee shortly after the return to the colony, and at first it was intended that the committee should publish it at its own expense and under its own authority, but eventually it was deemed more judicious to widen the basis of the scheme, and to ask the Government to undertake this task, as it was likewise felt that, if the autho rities, were to do so, the miners of the whole colony would be enabled to secure the valuahle information obtained at the expense of the subscribers on Bendigo. The Treasurer, the Honorable Graham Berry, M.P. (Premier), agreed to do this in conjunction with the Hon. W. Collard Smith, M.P., Minister of Mines, and thus the manuscript report, together with its nu merous diagrams, was then submitted to the Secretary for Mines, Major Couchman, C.E., for examination, and with a view of estimating the cost of its publication, and reproduction of the diagrams accompanying the text.

It was found, however, that to do so would necessitate an outlay of about six hundred pounds sterling, and as that amount exceeded the anticipations of the Government, the Honorable the Minister of Mines agreed, in reply to questions put to him by Messrs. Kobt. Clark, Jno. Maclntyre, and the Hon. A. Mackay, M's.L.A., during the session of 1878-9, to obtain an amended and condensed report from the delegate, and, by omitting most of the diagrams, sketches, &c, on account of their being too expensive to reproduce, to considerahly reduce the cost of the publication. This has been done, and this present synopsis of the original report is therefore published with the sanction and by direction of the Honorable the Minister of Mines ; and the delegate trusts that his work in its present form may be favorably received, so that, contingent thereon the whole of the diagrams, sketches, &c, now laid aside for possible future use, on the score of economy, may he added to a future edition, together with the copious descriptions which will in that event be necessary.

MINING IN CALIFOENIA AND NEVADA. 3 As regards the classification of the subjects treated in the present publication, the delegate found it necessary, under the altered circumstances of the case, to depart from his original instructions, as the latter were drawn up somewhat ambiguously, and therefore the following course, as more practical, has been adopted, viz. : — To first describe the geological and mineralogical features of the country, with their metalliferous deposits and lodes ; then to investigate and take note of the operations in the latter from their displacement by the miners, by means of various operations and appliances, through their subsequent manipulations to the final resultants of commercially valuable metals and other products, as well as the rejected wastes at the conclusion of the whole process.

In describing the various matters connected with mining in America, and submitting my views for adoption here, it is not intended to convey an impres sion unfavorable to what we may have become accustomed to from actual prac tice, but rather to give the thinking portion of our mining community an opportunity to read, compare, and form their own judgment as to which of the two systems — viz., the Victorian or the Californian — is preferable, and what should be adopted of either, or what should be rejected. "THE DELEGATE." CONTENTS. Part 1.— CALIFORNIA. Section 1. — Geological Features : Gold-bearing Quartz Lodes ; Auriferous Slates ; Diluvial Gold-bearing Gravels and Deep Leads. Section II. — Mining Operations : Sinking of Shafts ; Driving Levels ; Pumps ; Air Com pressors ; Percussive Rock-boring Machines ; Diamond Drills j Ventilation.

Section III. — Boilers ; Winding or Hoisting Machinery ; Safety Catches and Safety Hooks. Section IV. — Mining and Crushing Auriferous Ores. Section V.— Various Methods for Treating Crushed Quartz ; Retorting. Section VI. — Reduction of Pyrites : (a.) Common Roasting and Grinding ; (/<.) Chlorination ; (c.) Other Processes ; (d.) Sampling and Assaying of Ores. Section VII. — (a.) Hydraulic Mining of Auriferous Gravels ; (b.) Drift Mining by means of Shafts and Tunnels. Appendix. .4. Novel Treatment of Poor Copper Ores. B. Asbestos and its Uses. C. Wages. D. Mine Timber. E. Mining Laws. F. Schools of Mines. Part H.— NEVADA. The Comstock Lode. Section I. — Geological Features Section II. — Mining Operations. Section III. — Pumping Machinery ; Ventilating Machines, or " blowers " and exhaustors.

Section IV. — Crushing Mills : (■<.) Concentration and Amalgamation ; (A.) Modes of Treatment. Section V. — Tailings. Section VI.— -The Sutro Tunnel. Appendix. A. Wages. _5. Mining and other Laws. C. Minerals aud Ores. L). Mine Timber. GEOLOGICAL SKETCH OF GRASS VALLEY, CALIFORNIA. Part I. CALIFORNIA. Section I. — Geological Features. In confining myself in this paper to the really metal-producing districts visited in the State of California, I may, however, in passing state that that country is traversed nearly north and south by the Sierra Nevada Mountains, which obtain an altitude of over 8,000 feet above sea-level. The western slopes comprise California, whilst to the east the State of Nevada is located. The base of the Californian side is formed of Tertiary drifts or gravels, which partly constitute further inland the " Foot-Hills," or one of the terraces rising above the fertile lands along the Sacramento and other rivers.

Above these foot-hills, the country becomes rapidly more and more mountainous, and thus the gold-bearing regions occur at an elevation varying from 2,000 to 4,000 feet above the Bay of San Francisco, forming au almost uninterrupted metalliferous belt, not only within California proper, but likewise in portions of Arizona in the south, aud Oregon territories in the north, extending many hundreds of miles in those directions. Having explored, as far as my time would permit, the following counties in the State — viz., Nevada, Sierra, Calaveras, Tuolumne, and Mariposa — it will be seen that these areas cover a large extent of country, which, however, do not include all the other mining regions equally worthy of notice, but which I was prevented from visiting during the three months only at my disposal iu America.

In all the counties visited, however, nearly the same geological features were observed, with but few unimportant departures from the general character and position of the country rocks and the quartziferous gold-bearing lodes those rocks enclosed. And, as the well-established quartz mining district near Grass Valley City, Nevada County, attracted my first attention on account of its leading position amongst the others, a concise description of the place will, I submit, suffice for all present practical purposes, and at the same time elucidate the condition, geologically consi dered, of other aud similar mines as well (Plate No. I.). The Kate Hayes mine, south-west of the City of Grass Valley, is situated upon an eminence, which permits of an extensive view up to the snow-clad Sierra Nevada in the far distance, and, in the more immediate neighborhood, of all the mines worked or in the course of exploitation ; besides, the first mentioned mine occupies a position on that central belt of coarse feldspathic granite bearing N. 20° E., which divides the sedimentary and metamorphic rocks as well as the serpentines and syenites, which latter occur here as the enclosing or " wall rocks " of nearly all the quartz lodes, with this difference, that the strike of the first-named is nearly due east by west with frequent alterations, thus differing materially from our regular Silurian strata at Bendigo and elsewhere.

The arrows in black shown on the chart at the lodes named and delineated, denote both their dip and underlay, which, it will be seen, not only varies considerably, but demonstrates besides a total want of regularity and continuity in the line of strike such as we are accustomed to in Victoria, and which circumstance, in California, is doubtless B due to the numerous upheavals of the granites and other eruptive as well as less active Plutonic rocks. The only regular " line " of a lode resembling those on Bendigo, Castlemaine, or Climes, is situated about four miles south south-east of the central station, or Kate Hayes mine, and that line is com posed of a number of semi-detached blocks, lenticular in form, each of which, however, contains a distinct "pay-chute," or "shot of gold," all clipping south with a western underlay varying from 29 degrees to 40 degrees.

GOLD-BEARING QUARTZ LODES. The line referred to is worked by the new Franklin, Homeward Bound, Omaha, and other companies, and is located in Wolfs Creek, and, higher up the same range, about a thousand yards west, another rich lode is in full operation by the New York Hill Company, and their lode, with an eastern underlay, would therefore form a junction with the first-described line at a not very great depth, both lodes being synclinical in their respective underlays. The strike of the New York lode varies, however, as much as its underlay, the former being N. 25° E., on an average, whilst at the south shaft the underlay is from 17| degrees only to 37 degrees. Perhaps the most regularly defined and best formed continuous lode in California is that of the Idaho Company in this vicinity, as will be seen from the following table, showing the underlay, viz.: — The first 200 feet at an angle of 67 degrees west 200 to 400 „ „ 65 „ „ 400 „ 500 „ „ 62| „ 500 „ 700 „ „ 6o „ „ 700 „ 1,000 „ „ 00 „ The dip of the cap of this lode to the south averages about 34 degrees, which, with the vertical height of same at 600 feet, gives over 1,400 feet in length by an average width of 7 feet for this immense "pipe vein" (American), or block of quartz.

Its hanging wall is composed of a dense green . chloritic schist ; the dyke of serpentine at the foot wall renders the working of this lode very expensive, on account of the serpentine swelling in ojaen air, being largely impregnated with lime, by meaus of which the timber is forced against the hard schist at the hanging wall, and is rapidly destroyed. The quartz has that peculiar seamy character so much liked by our Bendigo miners, and in these more or less slaty laminations free gold, of various degrees of coarseness, occurs, besides iron and copper pyrites. The richness of this lode from its outcrop in Wolf's Creek, where it was held by the Eureka Company, now " shut clown " or abandoned, to the present Idaho boundary, was clearly proved to me several times by the Messrs. Coleman Bros., part owners and superin tendents, exhibiting many specimens which, in large pieces, contained more gold than quartz.

The Californian quartz has, on the whole, a very similar appearance to that in Victoria, being seamy and bluish-white in color, but frequently it is stained by the green carbonates of copper. The gold is both coarse and fine, the latter predominating, however, in most lodes, and then it assimilates to that found in the Maryborough and Stawell districts. Another but very narrow lode is that of the Empire Company ; in fact, there are here two parallel veins dipping north ; the east vein having been found very profitable to work. (I saw, myself, ore* broken down at the 1,100-foot level * All quartz containing gold or silver is termed "ore" by the American miners. estimated at 10,000 dollars in value ; and I may here remark that the Ameri cans do not calculate the outcome of their crushings as we do in ounces, pennyweights, and grains, but they reckon the intrinsic commercial value of the gold, &c, per ton in dollars.)

The east vein alluded to has been worked for a length of over 2,800 feet to a depth of 1 ,236 feet for an average width of 1 5 inches, the angle of underlay west being 31 degrees. There were other mines at work, such as the Centennial and others, all paying very well, whilst others were idle on account of heavy underground water. All the lodes thereabouts were highly charged with sulphurets, chiefly of iron, copper, and lead ; arsenic, zinc, and antimony being more of a rarity than in our mines. In the neighboring mining district of Nevada City, the municipal centre of the county, nearly all the quartz lodes occur in the granite, which forms the country rock principally, except on the south-eastern side of the Bear's Creek Valley ; and, of the mines inspected, the New Providence forms a very good example of how auriferous quartz lodes in pure granite country may occur with a regularity and permanency that should be instructive to miners engaged in a like country.

This company's lode underlays a little north of east at an average angle of 38 degrees, and it was, at my time of visit, worked 800 feet in depth, having, moreover, been traced by several companies and worked for one mile and a half in length, with an average width of 6 feet. The hanging wall has a very peculiar appearauce, by exhibiting strongly marked and clean polished striations, presumably the result of intense friction ; but there is in this case no corresponding foot wall, as the main bodies of ore run into the underlaying country rock, where they split into numerous veins, decreasing gradually in size, but are still gold-bearing for a distance of over 60 feet from the main back. It has been found the rule here and elsewhere in the State that, when these lodes assume an eastern underlay, the "makes" of quartz, stone, or ore dip north; and, if the lodes underlay west, the opposite dip of such "makes," &c, obtains.

South of the main shaft (New Providence Company), in the 600-foot level, no less than three of these makes of ore occur, and, as they are accompanied by a soft "selvage," or "flucan," at the hanging wall, it is a very remarkable circumstance that, in these makes of ore of a lense-like form, concentric laminations occur, which correspond thoroughly with the outer lines of each block, and these laminations are strongly indicated by bands of very rich sulphurets (they yield by chlorination after concentration from 60 to 100 dollars per ton). This ore resembles that of the St. Arnaud mines, and also of that strong block of nearly pure pyrites at the 600 and 700-foot levels of the Lazarus Company, Bendigo. In this Nevada district the upper portions of the quartz lodes, embedded in softer country than deeper down, were very rich in free gold ; but gradually harder country appeared with greater depth, and a very decided modification was manifested, for the quartz depreciated gradually in value in proportion to the greater prevalence of the . incoming denser wall rock.

An opinion prevailed then that these "ledges" as they are termed in California, would ultimately become quite barren of gold; but shortly afterwards all this was disproved to everyone's satisfaction, because, at greater depths, as rich auriferous sulphuret lodes have been found in as hard wall rocks below the water-level as where such were of a kinder character, as the miners would say. The fact of the matter was simply this : that, with o-reater depth in a harder country, the free gold at the shallower levels became associated with sulphurets, which latter prevented the old methods for o-old extraction to be as successful as they had been during the treatment of the ore with free gold only, occurring at the higher levels. It may also be remarked that these ledges are found in extensive belts of granite, which run west and east, and as the lodes strike north by a little south, besides exhibiting other characteristics, it may be safely inferred that they are true fissure veins, according to Californian theories, and therefore permanent.

This view is strongly supported by the fact that numerous blocks, or "makes," as described above, formed against the "main back," were worked by this proprietary, and that, at their bottom level (800 feet), another block had just been cut into, resembling all those at the higher levels ; this new discovery proved, after proper tests had been made of the ore, exceptionally rich in gold-bearing pyrites. There are quite a number of mines here also located in the granite country, but, as their general character resembles that which has been said of the New Providence mine, I consider all present purposes of this paper have been served, and consequently I proceed to the description of mines differing from any hitherto referred to. The Pittsburg is situated a short distance east of the granitic belt, in which the New Providence and other mines are located, and about three miles south of that mine ; this lode, however, occurs in a kind of coarse sandstone, which is farther on metamorphosed into greenstone syenites, traversed by strong dykes of diorite, highly crystalline and easily distinguished at the surface.

I reo-ret not havin°- been able to investigate these interestino features more closely, owing to the short time at my disposal, especially as this formation would ultimately join a belt of lodes in the south, occurring, however, in chloritic schists and serpentines ; the time at my disposal would be utilized by the more practical matters, of which the elaborate treatment of the quartz after crushing would engross all my attention. This Pittsburg lode ranges from 15 inches to 3 feet in width, and the ore averages from 20 to 50 dollars per ton, inclusive of the 5 per cent, of sulphurets it is charged with. The latter, after careful concentration and chlorination, have, however, given as high as 110 dollars per ton (American ton, 2,000 lbs.). In this mine the same rule has been found to prevail as mentioned in regard to the behaviour of the blocks of ore on a western or eastern underlay, thus affording a field for geological deductions as to the dynamic and kindred forces in action previous to, during, and since the formation of these and similar metalliferous deposits.

As regards the frequently discussed and mooted existence of " barren zones," or country at one time very prolific in rich ores becoming quite devoid of such ores, I may state that I have arrived at the conclusion that these are only temporary occurrences if compared with what I saw in California. After careful examination, I offer the following conclusions for consideration, as tending to dispel doubts, and, instead, to encourage " deep quartz mining" with more confidence of success and for permanent results than many regard the stability of our lodes in Victoria : — 1st. I observed no "saddle" or anticlinal reefs or ledges in California. 2nd. That in California isolated lodes were more frequent than they are here in Victoria. 3rd. That in a few instances a " line of reef," in the Bendigonian acceptation of the term, was found to exist, but that these lodes were iu themselves very irregular, and that the barren country intervening betwixt the blocks or makes of ore would amount to as much as the actual quantity of gold-bearing quartz. 4th.

That in California the occurrence of payable ledges was subject to more irregularity than, generally speaking, in Victoria, 5th. That, owing to the nature of the mountainous mining regions, a much greater number of gold-bearing lodes Avere exposed at the surface in California than in this country, though this circumstance would be, to some extent, counterbalanced by the greater regularity, continuity iu the lines of strike, and easier-working country observed with our Victorian quartz reefs. 6th. That the Californians, in order to overcome all difficulties, and also the equally great question of treating their crushed quartz, which contains certain ingredients detrimental to perfect gold extraction, have adopted and are continually perfecting a very superior method for treatment of such quartz, which latter, I submit, serves the purposes intended admirably.

The ledges located and worked in the more southern counties of Cali fornia — viz., Calaveras (part only visited), Tuolumne, and Mariposa — proved on investigation to be similar to those already described ; but as in all these mining regions the term " mother lode of California" is much used, it may be as well for me to explain that phrase, as it means simply a characteristic succession of strongly developed outcrops of auriferous quartz, of more or less value, frequently rising above the surface in ponderous masses to a height approaching 60 or 80 feet, and invariably almost stained green from carbonates of copper. And as these masses of quartz are of considerable thickness, and, besides, surmount the more prominent mountain peaks, their appearance for many miles has found what may be considered a very appro priate appellation.

We, in Victoria, would be justified, I think, on nearly as good grounds, if we were to term the continuation of the Bendigo lodes throughout the Castlemaine, Taradale, Daylesford, and Blackwood districts the " mother lode of Victoria." The country rocks in the Californian gold districts differ unmistakably from those found in contiguity with our Victorian reefs. Near Grass Valley they are mostly highly metamorphosed schists or sandstones, passing into diorite or greenstone syenite, all of which are charged with pyrites of iron ; and in other districts the country rocks belong to the chlorite, talc, and hornblende groups of schists. The marked difference thus exhibited does not, however, in any one case extend to the gold-bearing lodes, which, as already stated, resemble very closely indeed those worked in Victoria.

Many times, underground, I could not see any difference between our reefs on Bendigo, Clunes, and Stawell, though I well knew I was examining Californian ledges all the time. The only place where I observed true Silurian slates and sandstones, with faint traces of " graptolites " and allied petrifactions in the wall rocks, was at Tuttletown, Calaveras County. In these slates, &c, a very similar formation to that worked at Snob's Hill, Eaglehawk, was visible ; but, instead of the heavy gold generally found in the° spurs worked near Eaglehawk, this Californian quartz contained that very peculiar kind of " leaf gold " which fills the crystallized cavities of their quartz, and is of course very light, and therefore difficult to collect. (Marks and Durrow mines.) In the Mariposa County, adjoining, near Coulterville City, the Merced River has, during the process of its erosion, disclosed many valuable quartz lodes where that river intersects the "mother lode" with its numerous parallel ledges.

Amongst these, the following deserve notice, viz.: — Pine Tree, Anderson, Crown Peak, Adelaide, Midas, Ealston, and others. All these have, time after time, given excellent returns to considerable depths from the surface, and, right here, the continuity of lodes to a great depth has been proved in a very convincing sort of a way. As this is a very mountainous region, the valleys are frequently from 1,000 to 2,000 feet deep, and from the summits of the mountains down to their base these reefs are exposed to view, maintaining the same width and extent of each "pay-chimney" or "chute," or the blocks in which they may be enclosed, with the aggregation of richer, poorer, or worthless quartz, the same as in Victoria. Comparing the yields, as taken from many official records, a similar fluctuation is observed as with us, and, as this may be of some interest, I append a short statement obtained from the books of the frequently mentioned Idaho mine, Grass Valley City, showing the yield of various levels, viz.: — ■ At and above the 300-foot level, which was worked by the Eureka Com pany, the average yield was returned at 100 dollars, i.e., about 5 oz. of gold per ton.

The 400 and 500-foot levels were poor for the whole extent worked, whilst the 600, 700, and 800-foot levels produced quartz that fluctuated from 25 to 35 dollars per ton. The 900-foot level averaged about 35 dollars; and the 1,000-foot, according to late advices, state that a higher average is being obtained from this company's deepest level. The Alaska mine, in the same locality, had also very rich ore in the deep ground ; the Pittsburg and New Providence, Nevada County; the Rising Sun, Colfax ; the Golden Gate, Sonora City, Tuolumne County; the Banderitos, Skendlin, Marble Vein, Haslon, Derrick, and others, near Coulterville, Mariposa County, all exhibited this same satisfactory feature in their bottom levels. On the whole, I may state that, in most of the Californian mines I have inspected, the quartz looked and yielded as well, and in many cases better, in the deep ground than it had done nearer the surface.

I took particular care and trouble to assure myself of this fact, by reference to the official reports and accounts kept by the mine superintendents and secre taries, and I submit that this information should be of value to us in our deeper mining operations. AURIFEROUS SLATES. These remarkable formations have given rise to extensive operations near Coulterville and other places. The Ferguson Company, near the former city, was successfully engaged on a vein or stratum nearly vertical in position ; and this talcose, friable slate was impregnated with thin, flat, and very fine flakes of gold for a varying thickness of the vein of from 12 inches to 6 feet. Owing to the frangible nature of this slate, and on account of the light character of the gold in it, which, after crushing, formed a "pulp" of very little specific gravity, the utmost care had to be exer cised both in the concentration and amalgamation of these atomic grains of gold.

I would not have referred to this remarkable occurrence, or have described lower down the process adopted for treatment, were it not that frequently our Bendigo lodes diminished first in size, and then passed gradually into a soft, deep-black slate (flucan), also impregnated with very fine gold, which we cannot very successfully collect with our appliances ; so that, by adopting the Californian method, we might add to our yields of gold from similar formations. DILUVIAL GOLD-BEARING GRAVELS AND DEEP LEADS. These important deposits are very appropriately termed "ancient rivers" iu California, aud the extent of their extensive watersheds must have been, at that remote period, very considerable, to judge from the various points, many miles apart, where they have been subjected to mining operations on almost a gigantic scale.

And it may also be observed that in but two instances the working of deep leads beneath the basaltic or trappean coverings had been taken in hand, although "bald hills," capped with porous and dense basalt, and underlaid with Tertiary drifts of as pronounced a type as at the Loddon, Ballarat, Charlotte Plains, Creswick, &c, were frequently passed over during my peregrinations. The ancient rivers of California somewhat resemble our deep leads, with this difference, that, in most cases, the modern water-courses have cut their way into the bed-rock below the older river beds, and which latter are filled with the detritus of rocks evidently brought along by either fluvial or glacial action. In this manner these valuable deposits assume frequently, through the intersection of the present drainage system of the country, the aspect of our made hills, whereas, in reality, they are but the severed parts of a network of ancient water channels now altogether obliterated and filled with Pliocene gravels or drifts.