Proceedings of the Tomsk Technological Institute of Emperor Nicholas II,
Vol. XX, 1910, No. 4.

The Bogom-Darovanny Mine,

in the Achinsk Mining District.

(Preliminary report on the summer assignment of 1908).

With 2 tables and 1 figure in the text.

P. P. Gudkov.

In the summer of 1908, by the Council of the Tomsk Technological Institute, I was assigned to the gold mines of the Achinsk and Mariinsk mining districts for the period from July 15 to August 15. The purpose of the assignment was a detailed geological investigation of the Bogom-Darovanny mine of K. I. Ivanitsky and the Berikul mine of A. D. Rodyukov. In view of the protracted geological excursion with students in the vicinity of Krasnoyarsk, in which—together with Prof. V. A. Obruchev—I participated as a leader, and then because of a delay in receiving the funds for the assignment, I was able to leave Krasnoyarsk only in mid-July and arrived at Bogom-Darovanny on the 22nd of that same month. During the interval from that day until August 12, the areas of Bogom-Darovanny and the 17 allotments adjoining it were examined (altogether about 18 square versts), and the workings of the Bogom-Darovanny mine, as well as the prospecting workings on the allotments of the Podlunny, Podoblachny, Podzvezdny, and Bogoroditse-Rozhdestvensky mines, were also studied.

On August 12, while inspecting old workings in the main adit of the Bogom-Darovanny mine, I fell from the upper level to the lower one and injured my leg, owing to which I was compelled to stop work and, after remaining at the mine until August 24, to leave for Tomsk, still not being able to walk freely. Thus, I was unable to visit the Berikul mine, and the assignment was limited to the above-mentioned work at Bogom-Darovanny.

The absence of a sufficiently complete and accurate topographic map, together with the limited time that I could devote to the study,

the Bogom-Darovanny mine—compelled me to limit my work to a detailed examination of all the mine workings and to a geological survey only of the environs nearest to the mine. In favor of such a plan there was also the fact that, in the very same summer, a geological investigation of the entire system of mines of the Achinsk Mining District was being carried out by Siberian geological parties which, having approached Bogom-Darovanny with systematic investigations of so extensive a region and possessing good topographic maps, can undoubtedly provide a more thorough geological map. For an investigation of the deposit itself as such, for the study of the underground workings, these parties did not have sufficient time.

In the geological survey of the surface I used a copy of a map compiled from allotment plans at a scale of 100 sazhen to one inch, taking the allotment posts as control points for my survey, since they had been plotted more accurately. (In all other details, in addition to being very few in number, the map I had proved to suffer from considerable inaccuracies.) In most cases during excursions I conducted the survey with a mining compass with diopters, measuring distances by pacing. On some of the more interesting routes, however, distances were measured with a tape. In this way, for example, all prospecting trenches were surveyed. Elevations were determined by two medium-sized aneroids and were calculated relative to the manager’s house (near the astronomical point), where the readings of the same aneroids were observed daily before and after each excursion.

In investigating the underground workings I used surveyors’ plans, kindly placed at my disposal by the mine manager, A. E. Dedokhin. The investigation of the underground workings consisted in making sketches of the faces and, in general, of the exposed surfaces of the workings, and in collecting specimens from all points where loose debris did not prevent this.

The total number of specimens collected and delivered to the geological cabinet of the Institute was over 400, not counting duplicates and museum specimens.

Throughout my stay at the mine I received the most courteous assistance from the administration, and therefore I express my deep gratitude to K. I. Ivanitsky for the hospitality shown; to A. E. Dedokhin, who placed a horse and a workman at my disposal and communicated much valuable information from his observations; to A. F. Putalov, who repeatedly accompanied me during the inspection of the workings; and to mining engineer N. Ya. Verevkin, who constantly assisted me

…by me in the work and completed, after the accident that befell me, the examination of several levels of the main adit.

The Bogom-Darovanny mine is situated 25 versts (in a straight line) south of the village of Pokrovskoye and is located at the head of the Bezymyanny (otherwise Fedorovsky) spring, which flows in from the right into the Bolshaya Sobaka River—the left tributary of the Syya, of the White Iyus system. The orography of the environs of the Bogom-Darovanny mine is distinguished by the same sharp dissection of relief that characterizes the entire mountain knot beginning near the village of Pokrovskoye and representing—apparently—the northern spurs of the Kuznetsk Alatau. The valley of the Fedorovsky spring is narrow, deep, and has a considerable gradient, especially in its upper part. The latter is situated on the northern steep slope of a pass which forms the watershed between the Fedorovsky spring and the headwaters of Saktychul. From the west and east the valley of the Fedorovsky spring is bounded by high and steep spurs of the same watershed. The western of these spurs, separating the Fedorovsky spring from the Sobaka River, descends to the northeast toward the confluence of these streams as a rather steep promontory; in its southern part, in turn, it divides into two spurs, of which one passes between the left-hand headwaters of Solgon and Saktychul, while the other, turning sharply eastward, joins, by means of the above-mentioned pass, the eastern spur separating the Fedorovsky spring from the Vesely spring. The greater part of the area investigated is almost entirely devoid of forest and abounds in outcrops, often in the form of rather high (up to 10 sazhens) cliffs, as, for example, on the eastern side of the pass between the Fedorovsky spring and Saktychul (on the map, the point with an elevation of 609 sazhens) and on the left bank of the Sobaka opposite the mouth of the Fedorovsky spring (the point with an elevation of 431 sazhens).

In geological respect, the area investigated by me, as may already be judged from the map, is not distinguished by great variety in the rocks composing it*). The greatest distribution belongs to igneous rocks, and among them especially to greenstones, representing various structural modifications. Here we find also a normal diorite of hypidiomorphic structure and of varying grain size; and a porphyritic diorite rich in hornblende, with sharply projecting regular white crystals of plagioclase; we find also typical diorite porphyrites, and, finally,

*) The determination of the rocks has so far been made on the basis of only the very cursory examination of thin sections prepared from the most widespread rocks (20 thin sections in all).

tuffs of the latter. However, of all these modifications only two, apparently, play a more or less independent role: porphyritic diorite and the porphyrites with their tuffs. As for the diorite of normal structure, it has so limited a development and gives such gradual transitions into porphyritic diorite that it has to be regarded merely as local structural varieties of the latter. Moreover, as will be seen below, in some cases the rationality of separating porphyritic diorite from the porphyrites appears doubtful.

The latter compose both slopes of the valley of the Fedorovsky spring, as well as the southern and western slopes of the ridge that separates this spring from the valley of the Sobaka River, and somewhat above the mouth of the Fedorovsky spring they pass southward onto the left bank of the Sobaka. In the majority of cases these porphyrites are a grayish or bluish-greenish rock, almost completely aphanitic and lacking macroscopically distinct porphyritic segregations. Very often they contain fairly abundant—up to the size of a hazelnut—amygdales of calcite or chlorite, or cavities of the same size. In the latter case these rocks, even microscopically, more closely resemble tuffs. The microscope, however, reveals traces of a fragmental structure even in those specimens which at first glance seem completely homogeneous. Thus, for example, in a thin section of a specimen taken from the right side of the Fedorovsky spring near its channel (on the map, the point marked with an elevation of 410 sazhens), we see a very fine-grained groundmass consisting chiefly of fragments of chlorite and, in smaller quantity, grains of quartz and feldspar (the latter partly in the form of thin laths of plagioclase); scanty and small segregations of considerably calcitized plagioclase and many irregular, but rather sharply bounded areas consisting of a chloritic groundmass rich in ore particles and of small porphyritic segregations of plagioclase. The presence of such inclusions, undoubtedly belonging to the same dioritic porphyrite, together with the distinct bedding often observed in the rocks under consideration, compels one to suppose that several successive outpourings of one and the same magma took place here.

In other cases we also find completely homogeneous in structure and more typical dioritic porphyrites with various plagioclase segregations already visible macroscopically. This latter variety is for the most part (if not exclusively) encountered near the boundaries of the porphyrite with the porphyritic diorite and is, as it were, a transition to the latter.

Near the boundary with sedimentary rocks, the porphyrites and their tuffs contain inclusions of a black, dense, and hard hornstone-like rock, which gives them a breccia-like character. Finally, it should be noted that near the same boundary the porphyrites are strongly enriched with pyrite, which, however, is in general a fairly constant admixture in these rocks.

On weathering, the porphyrites produce a dense yellowish-green crust, which makes it possible to distinguish their outcrops even from a distance. The varieties enriched with pyrite, however, on weathering pass into a brownish-yellow earthy mass, so unlike the original rock that its genetic connection with it could be established only on the basis of samples taken from prospecting trenches, which reveal, step by step, all stages of weathering.

As has already been mentioned, in some cases, within a very limited area, such gradual transitions are observed from the porphyrites just described to porphyritic diorite, and the replacement of outcrops of the first rock by the second is so frequent and inconspicuous that it is not everywhere possible to distinguish the latter on the map. Such, for example, are the areas on the right side of the Sobaka near Ugolny Spring and on the left bank of Fedorovsky Spring, about 200 sazhens below the buildings of the upper camp. The exposures of porphyritic diorite near Ugolny Spring may perhaps also be connected with outcrops of the same rock on the hill between the Colorado and Zashirotny claims; in that case we would obtain a continuous belt of porphyritic diorite extending through the whole investigated area from SE to NW, but it would still be difficult to mark the boundaries of this belt in its northwestern part. Conversely, in the southeastern part of this belt (within the claims of Podzvezdny, Kaliostrovsky-Podlunny, part of Verkhne-Saktygulsky, Felonidinsky, Bogom-Darovanny, and the eastern part of Podoblachny mines), I considered it possible to show the porphyritic diorite for the following reasons:

a) in this area the rock in question has an exclusive distribution, with the almost complete absence of exposures of other rocks;

b) along the boundary of the porphyritic diorite and the porphyrites, marked by a dotted line, outcrops of the latter are often found, containing inclusions of porphyritic diorite;

c) the same boundary is marked as a line of more or less sharp replacement of one rock by another;

d) The porphyritic diorite in the workings of the Podlunny, Bogom-Darovanny, and partly Podoblachny mines is a rock that includes quartz veins.

In the great majority of cases the porphyritic diorite is a dark-green rock with a fine-grained groundmass, consisting chiefly of green hornblende, which has (as is shown by microscopic examination) probably undergone secondary origin, with plagioclase taking only a minor part; the phenocrysts belong to rectangular laths of cloudy and dull, more rarely colorless and lustrous, plagioclase. Under the microscope the groundmass proves to have a prismatic-granular structure and to contain, besides the macroscopically recognizable elements, a few ore particles, grains of quartz, and epidote. The plagioclase phenocrysts are to a considerable degree penetrated by new formations of calcite and sericite; in other cases they are almost entirely fresh.

The structural modifications encountered in the rock described consist either in a reduction in the number of porphyritic phenocrysts, down to their complete disappearance, or in an increase in the size of the grains of the groundmass, whereby the rock gradually passes into normal diorite, or, finally, in a diminution in the size of the porphyritic phenocrysts, which, as has already been indicated, brings the porphyritic diorite closer to porphyrite. The latter modification is for the most part confined to the margins of the belt of porphyritic diorite indicated on the map and—further—is fairly well developed in the already mentioned areas (near the Ugolny spring and on the left bank of the Fedorovsky uval), as well as in the northeastern corner of the area studied, near the boundary lines of the Zakharievsky and Nizhne-Klyuchevsky allotments.

As regards the reduction in the number of porphyritic phenocrysts, it must be noted that this phenomenon in some places (for example, on the Podlunny allotment) is accompanied by a strong enrichment of the rock in hornblende, which not infrequently forms continuous interbeds, and at the same time is connected with the appearance of veins and veinlets of quartz. In this case, evidently, we are dealing already with a greater stage of metamorphization, which the rock undergoes when quartz veins are introduced into it, and of which more will be said below.

Within the belt of distribution of the porphyritic diorite, a site in the middle of the allotment of the Podzvezdny mine is of considerable interest, where exploration for magnetic ironstone was once undertaken. Here, over a small area, in addition to porphyritic diorite and its modifications already familiar to us, we find—on one side—diorite richer in feldspars, and on the other—dark-

a dark-green fine-grained rock, in outward appearance somewhat resembling peridotite and containing inclusions of magnetic iron ore. The latter either forms, as it were, schlieren-like segregations in this rock in the form of solid pieces up to the size of a fist, or, in the form of pea-sized grains, is enclosed in quartz veinlets cutting through the rock, or is breccia-like mixed with quartz and calcite. Finally, here too we find outcrops of quartz porphyry, which seems to cut the diorite and contains inclusions of its fragments.

The question of the mutual relations of all these rocks can be resolved only after a detailed study of the collected material; for the present I shall allow myself to express only the following suppositions, which, in my opinion, must above all be tested.

1) Can the presence of a melanocratic variety of diorite containing segregations of magnetic iron ore be explained by local differentiation of the dioritic magma?

2) Are not the quartz veins cementing pieces of magnetite, in respect both to the time and to the mode of their formation, analogous to the gold-bearing quartz veins of the Bogom-Darovanny and Poldunny mines?

3) Can the outcrops of quartz porphyry encountered in the described area be correlated with outcrops of the same rock in other places*) and with those porphyry tuffs and breccias which, as we shall see below, alternate on the allotment of the Bogoroditse-Rozhdestvensky mine with sedimentary rocks?

If the last supposition proves admissible, then all the outcrops of quartz porphyry may be regarded as belonging to one continuous vein cutting the belt of porphyritic diorite, and then yet another question arises: is this vein not genetically related to that granite massif which lies to the south of the area investigated?

I infer the existence of such a massif from the indications of Prof. Zaitsev, who, as is evident from his diaries**), encountered a fine-grained hornblende granite near the confluence of the Saktynul with the Solgon—on the left bank of the latter, and then near the mouth of the Solgon

*) Outcrops of quartz porphyry were encountered in two places among the porphyritic diorite, namely: on the area of the allotment of the Kaliostrovsky prospecting claim, at points marked on the map by the letter П. At both points the quartz porphyry is found in the form of small rubble, apparently representing an in-situ outcrop that has disintegrated.

**) “In the Achinsk-Minusinsk Taiga,” Tomsk, 1901, p. 15.

in the soil of the placer of the Leontievsky mine and, finally, farther upstream along the Syt’, where “the rock—hornblende granite of medium grain—crops out in large blocks.” In all probability, the outcrops I encountered of the same medium-grained hornblende granite, situated on the summit and on the slopes of the mountain between the summits of Saktychul and Solgon, also belong to this same massif. As for the northern boundary of this massif, I have drawn it on the map more or less conjecturally, partly because of the rarity of outcrops in the south-western part of the area investigated, which is covered with dense forest, and partly because of the incompleteness of observations.*)

Diabase porphyries have a considerably smaller distribution in comparison with the rocks described. They compose the ridge of the valley of the Vesely Klyuch and the mountains on the left bank of the Sobaka, beginning at the mouth of the Fedorovsky Klyuch and lower down along the course of the Sobaka. These are dense and hard bluish-gray or greenish-black rocks with a conchoidal fracture, having the outward appearance of a basaltic habitus. Under the microscope, however, thin sections of them reveal a groundmass of intersertal structure, consisting of small laths, lying in various directions, of considerably decomposed plagioclase, fragments of chlorite, and rather abundant small grains of quartz, apparently secondary; in addition, amygdules of calcite and chlorite are quite frequently encountered, as well as more or less regularly bounded brownish translucent grains, probably belonging to ilmenite altered to leucoxene. Porphyritic segregations—strongly calcitized plagioclase—are scanty and small, and often are entirely absent. The forms of the outcrops of these porphyrites are chiefly cliffs, reaching a considerable height (up to 15 sazhens) and broken by such regular thick-slabby jointing that from a distance they seem to belong to sedimentary rocks. The strike of this jointing is either south-easterly or north-easterly, at an angle of 20°; more rarely, south-westerly at an angle of about 65°.

Sedimentary rocks have, within the limits of the area investigated, a very insignificant development, appearing in the form of two small isolated areas: on the right bank of the Sobaka somewhat below the Fedorovsky Klyuch, and on the north-eastern slope of the ridge between this klyuch and the Sobaka.

In the first area the sedimentary rocks were found in an artificial exposure (on a raw roadside slope of the mountain) among outcrops

*) The rains that began in the first days of August forced me to take up the investigation of the underground workings before I had time to complete all the planned routes.

diabase porphyrites. Here they have a general dip almost due north (from NO—5° to NW—343°), at an angle from 65° to 80°, and consist of weathered porphyry tuffs permeated with limonite, often cut by thin veinlets of quartz and calcite, and of a thin bed of clayey shale, upon which the tuffs again rest.

In the second area the sedimentary rocks have been exposed by prospecting works in the allotments of the Bogoroditse-Rozhdestvensky and Podoblachny mines. Their dip here is, in general, very variable, but an easterly dip predominates, at an angle of about 37°. The easternmost and, apparently, uppermost member of the sequence of sedimentary rocks here consists of thin-bedded, ribbon-structured, metamorphosed siliceous-clayey shales, made up of regularly alternating grayish-yellow and black-gray bands. As we shall see below, these shales are gathered near the surface into small folds and include a quartz vein having a dip concordant with them. Farther to the west we encounter porphyry tuffs, likewise considerably altered and abounding in newly formed calcite, secondary mica, and limonite. These same tuffs, somewhat farther to the north, become denser and contain inclusions of dioritic porphyrite and clayey shale.

Still farther to the west and higher up the mountain slope (near the point marked with an elevation of 555 sazhens), a fine-crystalline grayish-black limestone is also exposed in prospecting ditches. Its thin sections under the microscope prove to consist exclusively of calcite grains, forming partly a honeycomb, partly a dentate structure, and to contain no traces of fossils. The thickness of this limestone is about 10–15 sazhens.

Beyond the limestone we first find the same altered clayey shales as were described above, and then a calcite-rich limestone-sericite rock, which, as one proceeds westward, becomes increasingly enriched in sericite and grains of quartz and is probably also a product of alteration of porphyry tuff. The latter, together with a breccia of microfelsitic quartz porphyry (a dense black rock containing fragments of dioritic porphyrite and clayey shale and abundantly impregnated with pyrite), forms the western boundary of the sedimentary sequence under consideration.

A distinctive feature of all the rocks listed, in addition to intense metamorphism, is their considerable pyritization. Among all the specimens collected here there is not a single one that does not contain a noticeable dissemination of pyrite; the porphyry tuffs and all the products of their alteration are especially rich in this mineral.

...formations—on the one hand, and quartz veins enclosed in these rocks and in clay slates)—on the other. In addition, a rather clearly expressed, most intense pyritization) is observed near the boundaries of distribution of the sedimentary rocks and, especially, near the western one: the band of dense black rock passing here (the breccia of microfelsitic quartz porphyry already mentioned) is so rich in disseminated pyrite that the latter can be noticed even at some distance from the outcrop**).

From the description given of the thickness of the sedimentary rocks it is evident that this thickness can in no way be regarded as something integral, either in mode or in time of formation of its individual members. The presence of tuffs of quartz porphyry containing fragments of clay slate undoubtedly indicates the different age of these rocks. Moreover, in some cases one may even doubt the rationality of applying the name “tuffs”: it is possible that we are dealing with true quartz porphyry, only including in abundance fragments of the rocks it has broken through. Therefore, in separating neither in the description nor on the map the tuffs from the sedimentary rocks, I was guided only by the close interbedding of the former and the latter and partly by the insufficiency of those data which can be obtained from a cursory examination of the collected material. A closer elucidation of the details of the geological structure of the area under consideration, as well as determination of the relations of the porphyry tuffs and breccias occurring here to the above-mentioned outcrops of quartz porphyry, I set as one of the tasks of the detailed report on my assignment.

In concluding the description of the rocks developed in the area investigated, it must also be said that a small thickness of sedimentary rocks—recrystallized limestones—is cut by the working adits of the Bogom-Darovanny and by the prospecting adits of Podlunny. Their position here is shown on the map by dotted lines. As is evident from the map, these limestones are enclosed here among porphyritic diorite.

I now turn to the auriferous quartz veins, and, for convenience, I shall describe them in the following order: a) the veins being worked of the Bogom-Darovanny mine; b) the veins being prospected on...

*) The latter sometimes contain, in addition to pyrite, also magnetic pyrites.

**) Extending, as we saw above, also to the adjoining igneous rocks.

***) It should be noted that outcrops of a completely similar, and in color equally reddish-brown, pyritized rock have also been encountered on the right bank of the Sobaka near Ugolny Spring. But it will be possible to connect these outcrops with those just described only after microscopic study of specimens from both localities.

Podlunnoye and c) the veins exposed by exploratory workings on the claims of the Podoblachny and Bogoroditse-Rozhdestvensky mines.

At Bogom-Darovanny at the present time two veins are being worked, the position of which is indicated on the map by the main adits. These veins are, properly speaking, two almost parallel branches of a single vein that was originally discovered. The average true strike of the latter (before its division) is SW—202°; beyond the branching both branches deviate toward the west, their average strike being: the eastern one SW—210°, the western one SW—205½°. The dip of the veins, while remaining in general steep (about 80° to the east), also changes somewhat, namely: up to the branching the vein dips eastward at an angle of about 80°; after the branching, the western branch in the lower worked horizons at first preserves the same dip, and then—also eastward, but less steep—about 70°; in the middle horizons, on the contrary, as one moves southward away from the branching, the dip of the vein approaches the vertical; finally, in the upper part, at first there is likewise an approach to vertical dip, and then a steep dip to the west. Such, in general outline, are also the changes in the dip of the eastern branch.

The thickness of the veins in the majority of cases is equal to 2–4 arshins, but in places reaches 10–18 and even 28 arshins (the latter refers to the places where both branches of the vein join). As for the structure of the vein, of which more will be said below, it changes almost at every step. The drawings of the faces presented in Table II sufficiently illustrate this.

Concerning the gold content in the veins and the changes in this content along the strike and dip, unfortunately, very little can be said. At the mine not only is no systematic sampling of ore from individual faces carried out, but there are not even recorded data as to which working the ore delivered to the factory from one or another series of faces comes from.* Therefore, for the time being one must be satisfied with information of the most general character, derived partly from the diaries of Prof. Zaitsev, partly from inquiries made of the mine manager, and partly from the “Collection of Statistical Information”

* This is explained by the factory’s insufficient capacity in comparison with the output, owing to which the ore delivered from the mine is first dumped into storage piles and from them periodically sent to the factory. It seems to us that it would be advantageous for the mine owners to establish a small stamp mill for the systematic sampling of faces. The costs of its installation and maintenance would probably be offset to a considerable degree by the gold thereby obtained and by a more rational direction of the exploitation work.

“On the Mining and Metallurgical Industry of Russia,” published by the Mining Scientific Committee. From the latter source we learn that the output of the Bogom-Darovanny mine and the average content of the ore treated were expressed by the following figures:

From Prof. Zaitsev’s diary we learn that the part of the vein before its division, during work in the summer of 1900, showed a gold content in the lower and middle levels— up to 30 zol., in the upper—** up to 40 zol.; in the faces of the adit along the western branch of the vein (on Plate 2, Fig. 1—levels \(k_1\), \(l_1\), \(m_1\))—in the lower and middle levels—up to 60 zol., in the upper—up to 48 zol.; in the faces of the adit of the eastern branch (levels \(h\), \(i\), \(k\)) in the lower and middle levels up to 30 z., in the upper—up to 80 zolotniks.

At the present time the southern faces on both branches of the vein are chiefly being worked. The gold content fluctuates rather considerably, in places reaching as much as 1 f. The richest are considered (according to the report of the head miner) to be the faces on the levels (see Table 2): \(f\), \(h\), \(l\) on the eastern branch, and among them especially the southern face (called the “3rd south”) of level \(l\). The southern faces (on the same branch) of levels \(a\), \(b\), \(c\), and \(d\) show an average content. In addition, according to the report of the same person, a zone stands out in the vein for its richness, dipping WSW at an angle of approximately 65–70°.

The rock enclosing the veins, as has already been said, is porphyritic diorite (and only in two places has limestone been intersected by underground workings). In the immediate vicinity of the quartz veins this rock exhibits various alterations, the nature of which can best be understood from the descriptions of the individual faces. Drawings of the latter are given on Plate 3, with

The Bogom-Darovanny Mine, in the Achinsk Mining District.

where, for each, its distance from the mouth of the lower adit is indicated; lowercase letters designate the working level, and the letters N and S the direction of the working (northern or southern).

From an examination of these drawings it may be seen that, near the veins, the enclosing rock most often passes either into a chloritic-limy rock or into a dense hornblende rock.

The first is a soft, and often greasy to the touch, greenish-blackish rock, usually with a noticeable schistosity and a considerable impregnation of pyrite. Sometimes it appears in the form of bands of varying thickness separating the vein from fresh diorite, and is then usually traversed by thin quartz stringers, in contact with which it is especially enriched in pyrite; in other cases it fills the intervals between individual parts of the vein (see workings d—S and f—N), or forms inclusions in the vein itself (working a—S); finally, this same chloritic-limy rock is found in all the cracks into which, in most cases, the vein is broken up. In outward appearance this rock does not remain everywhere the same: in some cases it presents itself as an almost completely loose clayey mass, while in others it still reveals the structure of diorite (workings m—S, d—S, a—S, c—N). The following should be noted as the general properties of this rock: it is undoubtedly a product of alteration of diorite; it forms—at least in the form of thin coatings—an almost constant selvage of the quartz vein and stringers (being absent only from stringers enclosed in the hornblende form of alteration of diorite); it fills all the fine cracks in the vein and everywhere, in contact with quartz, is strongly enriched in pyrite.

Another, no less frequently encountered form of alteration of diorite is a dense, hard rock of bluish dark-green color. Under the microscope it proves to consist almost entirely of hornblende, partly primary and partly secondary, of fibrous habit. Appearing now on one side, now on both sides of the vein, and also between the more massive stringers of a composite vein (workings l—S, a—S, f—N), this rock is most often encountered where the vein divides into many thin stringers. (If the drawings of some workings (g—N, d—N, e—S) seem to contradict this observation, it is only because in the indicated workings the quartz stringers are so thin and numerous that it did not seem possible to depict them.) In addition, for the form of alteration of the country rock under consideration, there is fairly clearly expressed a more or less constant condition of its occurrence in those workings in which both the vein and the enclosing-

the rock is not broken up by such numerous cracks as we find everywhere in other places. In contact with quartz (which here is, for the most part, quite compact—“massive”), the hornblende rock also contains a noticeable impregnation of pyrite, though in general to a much lesser degree than the chlorite-limestone rock. Under the same conditions, i.e., near the quartz, visible gold is sometimes also found in this rock.

As regards the rock marked in the drawings of the stopes (f–S, e–S, a–S, and g–N) by hatching of alternating solid and dotted lines, it should be noted that this yellowish- or greenish-gray rock almost never appears more or less independently anywhere; rather, being intersected by quartz veinlets and by cracks filled with chlorite-limestone rock, it determines the brecciated character of the portions of the stopes occupied by it. The color, compact texture, and considerable hardness of this rock lead one to suppose that it is the result of silicification and, in part, epidotization of the chlorite-limestone rock.

On three levels (n, m, and k), in the southern stopes, limestone was encountered. It has a black-gray color, a fine-grained texture, and contains an impregnation of pyrites. The content of the latter decreases with distance from the vein and increases in the other direction, so that near the vein the limestone already contains rather large inclusions of pyrites, while immediately between the limestone and the vein there passes a continuous band of pyrites up to \(1/2\) arshin thick (chiefly pyrrhotite, less pyrite and a little copper pyrites). In contact with the limestone, the vein becomes richer (up to 40 zol. per 100 p.).*) Like the other side rocks, the limestone in places also contains thin veinlets extending away from the vein, and in these cases it too proves to be auriferous. As may be judged from the communication of mining engineer Reutovsky,**) in addition to conditions entirely analogous to those just described, in workings of former years limestone was encountered “in the form of bands crossing the vein.”

From all that has been set forth above, the following general conclusions may be drawn.

1) According to the character of the rocks immediately adjoining the vein, the stopes in the underground workings of the Bogom-Darovanny mine are divided into

a) stopes in which, near the vein on both sides, we find chlorite-limestone rock, either still preserving traces of stru—

*) See Reutovsky, “Mineral Resources of Siberia,” p. 259.
**) Ibid.

...of the structure of porphyritic diorite, or else dense, but connected with the fresh rock by gradual transitions; in such stopes—in the majority of cases both the vein and the country rocks are broken up by an entire mass of fissures;

b) stopes in which the vein is bounded on both sides by a dense hornblende rock; here the vein most often appears to be complex, the individual stringers consisting of “massive quartz,” while the country rock shows no fissuring;

c) stopes in which on one side of the vein we find a chlorite-limestone rock; and, as a special case,

d) stopes with limestone.

2) Almost all the described country rocks of the vein show an impregnation of pyrite, which is most intense in the immediate contact with the quartz (and especially if the rim of the latter is chloritic rock).

3) Visible gold occurs: in the country rocks, always, however, in the closest proximity to the quartz; in thin veinlets of chlorite-limestone rock filling fine cracks in the vein; and in the quartz itself, where it is most often distributed along fine cracks cutting through the quartz. In general, the conditions under which visible gold is found somewhat recall those pertaining to the impregnation of pyrite, with the difference that I personally have never observed the latter in the quartz itself.

4) The stopes tested by me as the richer ones for the most part belong to types b and c (of those stated above).

Finally, it may also be added that the chlorite-limestone selvages of the vein often show mirror-like slickenside surfaces.

I do not yet have data on the gold content in the pyrites, but that, in general, the pyrites contain gold is already proved by the very existence of the cyanide plant at Bogom-Darovanny. This is also indicated by certain indirect considerations, such as: an increase in the gold content in the vein near the limestone, where, as was indicated, there is a whole belt of pyrites. In addition, the apparent increase in gold in the upper levels (as is seen from the indications of Prof. Zaitsev cited above) is probably also explained by the greater content of free gold formed from the decomposition of the pyrites.

At the Podlunny mine, at the present time, a quartz vein is being explored, discovered by two prospecting trenches and then cut by a shaft (see Table 4). The average strike of the vein is NE—19°,

the dip to the NW is very steep. The vein of solid milky-white quartz has a thickness of only about 1 arshin (in places somewhat more), but sends into the country rock a mass of veinlets of various thicknesses, which, winding in diverse fashion, retain the general direction parallel to the vein. In places, within the solid quartz, there appears, in the form of small lenticular inclusions and veinlets wedging out in both directions, a yellowish- or greenish-gray, dense and hard rock, already known to us from the description of the selvages in the workings of Bogom-Darovanny. This rock, in the majority of cases, is separated from the quartz by thin (up to 1 m/m) interlayers of fibrous hornblende. The country rock of the vein is a porphyritic diorite, which, as it approaches the vein, becomes more and more enriched in hornblende. Such enrichment is rarely uniform, but most often is expressed in the appearance, of varying thickness, of continuous hornblende interlayers bounding on both sides the quartz veinlets, so that in places where the latter are especially numerous there is sometimes observed a continuous alternation of layers of quartz and hornblende, with now the former, now the latter predominating in thickness. In the immediate vicinity of the vein, and also where it splits into separate, more substantial veinlets, there is found the same dense bluish-dark-green hornblende rock, which was likewise mentioned above. In contact with quartz this rock here too contains a considerable dissemination of pyrite, but on the whole less abundant than in the workings of Bogom-Darovanny. Conversely, visible gold is encountered at Podlunny in the country rock much more often and, perhaps, even more often than in the quartz itself, but, as everywhere, in immediate proximity to it. Pieces containing visible gold in the form of separate grains up to 2 m/m in diameter, or in the form of small grains grouped into small clusters or forming moss-like combinations, occur here, one may say, at every step; rarely, however, there are also found those in which the gold forms almost continuous smears up to 5 cm long and \(1 \tfrac{1}{2}\) wide.

As may be seen from the map, there are 2 more adits at Podlunny. At present no work is being carried on in these adits, and in their stopes only separate veinlets (up to \(1/4\) arshin thick) are visible, passing through the same porphyritic diorite enriched in hornblende as has just been described. Several small veinlets were also encountered in other places in the sides of both adits. The strike of the veinlets less often coincides with the direction of the adits, more often being perpendicular to it. The dip is more often to the...

easterly from 15° to 45°. Near the veinlets the country rock shows disseminated pyrite. According to Prof. Zaitsev,* the veins for which these adits were driven contained 10–12 zolotniks of gold per 100 poods of ore.

On the allotment of the Podoblachny mine there are several prospecting ditches, but at present they have all caved in considerably, so that I could observe only the rocks cut by these ditches; the data on the thickness and strike of the veins exposed here, and on their gold content, I borrow from the diary of Prof. Zaitsev (“In the Achinsk-Minusinsk Taiga,” p. 14). The veins nearer to the buildings of Bogom-Darovanny occur in altered diorite; they consist sometimes of white and dense, sometimes of cellular and ocherous quartz; they have a thickness from 1 to 1½ arshins and show a dip to OSO—100° ∠ 40°. Their gold content is sometimes about 50, sometimes about 20 zolotniks.

The westernmost vein (nearest to the boundary of the Podoblachny and Konstantinovsky allotments) occurs among breccias of felsitic quartz porphyry. The quartz in it is the same as in the preceding veins. In individual pieces** a gold content was observed from 5 zolotniks to 1 pound.

On the allotment of the Bogoroditse-Rozhdestvensky mine, prospecting work carried out during the past summer by mining engineer N. Ya. Verevkin exposed 2 veins. As already mentioned in the general geological sketch, these veins occur either in altered clay shales, or in porphyry tuffs, or have the former of these rocks on one side and the latter on the other. The prospecting has been carried to a depth of no more than 6 arshins and exposes only the upper terminations of the veins. Drawings of the two deepest shafts are given in Table 4 below.

The left-hand drawing depicts the northern wall of a shaft in which the vein occurs among shales. Cross-hatching indicates quartz (the vein and 4 veinlets); fine curved lines indicate the direction of the bedding of the shales; thick lines indicate fissures partly filled with small pieces of quartz; in the upper part of the shaft are alluvial deposits, beneath them—rubble of clay shale. From the drawing it is evident that the clay shales beneath the vein are gathered into small, but sharply bent and in places, as it were, torn folds. Along cracks along the axes of the saddles and troughs of these small folds, and also parallel to the bedding

* “In Search of Ore Gold,” p. 5, note.
** In dumps below the ditches.

the vein sends out thin offshoots. On the eastern and western walls of the pit the dip of the schists is the same \((\mathrm{SO}—93^\circ—94^\circ \angle 38—36^\circ)\) and conformable with the vein, so that the mode of occurrence of the vein may be schematically represented as follows (Fig. 1):

Fig. 1.

The vein quartz is yellowish-white, somewhat ocherous, and contains pyrite.

In another pit (No. 9) the vein is not at all visible, and only two small quartz veinlets are observed which, joining together, form on the wall of the pit something resembling the outline of a sugarloaf. The strike of the veinlets: the left one—SW—185° with a dip to the east at an angle of 80°; the right one—SO—179° at an angle of 56°. On the hanging-wall side we find a dense limestone-sericite rock formed from porphyry tuff, containing a noticeable dissemination of pyrite; on the footwall side—the same as in the preceding pit, altered clayey schists, apparently forming a small flattened fold; the rock is broken into pieces, cemented by a soft calcareous-clayey substance; the latter also fills the space between the quartz veinlets.

In the upper line of prospecting works of the Bogoroditse-Rozhdestvensky mine the vein was encountered by only one pit. The average strike of this vein is almost the same as that just described. The enclosing rocks are: on the hanging-wall side—altered porphyry tuff, cut by a rather thick (up to 2 vershoks) quartz veinlet and containing a fine dissemination of pyrite; on the footwall side—the same rock, but less altered and breccia-like, mixed with fragments of clayey schist; the dissemination of pyrite in it is more considerable. The quartz from the vein is yellowish-white, slightly porous, with smears of ocher and inclusions of pyrite, in places breccia-like mixed with porphyry tuff.

The sampling of individual pieces of quartz from the veins of the Bogoroditse-Rozhdestvensky mine, carried out by mining engineer N. Ya. Verevkin, showed the gold content:

in pieces from the lower vein: traces, 4 zolotniks, 8 zol. (per 100 poods);

” ” ” upper vein: 2 zol., 6 zol. and in one piece about 1 pound.

Thus, from the description of all the veins at present opened on the investigated area, we see that all the veins have almost the same strike, in most cases close to the meri-

dional; occurring in various rocks, they everywhere show a significant gold content; the rocks enclosing the veins show, in proximity to the veins, more or less significant alterations, in the vast majority of cases expressed in strong enrichment with carbonates, hydrous silicates, and pyrite (chlorite-limestone rock at Bogom-Darovanny, limestone-sericite rock at Bogoroditse-Rozhdestvensky), and also, at times, with other sulfides (pyrrhotite and copper pyrites in the limestone of Bogom-Darovanny); these alterations are confined to a comparatively insignificant zone, outside the limits of which only weak calcitization of plagioclase is observed in the porphyritic diorite (and even then not far from the veins; in other places this rock appears almost entirely fresh: the areas above Ugolny spring and in the northeastern corner of the investigated district); in any case, the alterations observed in the various rocks become noticeably more intense as one approaches the veins, and for this reason must be placed in direct connection with the latter, while, on the other hand, they manifest themselves over a larger space where there are several veins (by this must also be explained the strong alteration of almost the entire thickness of sedimentary rocks); visible gold, if it is encountered in the country rocks of Podlunny and Bogom-Darovanny, is always contained in one or another form of alteration of these rocks and, moreover, everywhere in immediate proximity to veins or veinlets of quartz. Therefore, regarding the genesis of the veins of Bogom-Darovanny and of the mines adjacent to it, I consider it possible to express the following views:

1) These veins are the result of the filling of fissures formed by the same tectonic processes that also caused the intense folding of the clay shales encountered at the Bogoroditse-Rozhdestvensky mine. At the same time it is interesting to note that the direction of this folding, as well as the general strike of the veins described, coincides with the predominant direction of the mountain elevations throughout the entire region of the Kuznetsk Alatau *).

The filling of the fissures was produced by the action of ascending thermal waters, saturated with silicic acid, carbonic acid, and sulfur vapors. This is proved by the above-described character of the decomposition of the rocks enclosing the veins and by their intense pyritization at the contact with the veins. The varied character of the alteration of the porphyritic diorite (its transition now into a chlorite-limestone, now into a dense hornblende po—

*) See Reutovsky, “Mineral Resources of Siberia,” Part 1, p. 4, and Sheet II of the map belonging thereto.

of the rock), probably depends on the greater or lesser mechanical disintegration of the primary rock: in those places where the latter had been broken up by numerous fissures, vapors of water, carbon dioxide, and sulfur evidently had freer access, which is why in such places (as was indicated in the description of the Bogom-Darovanny workings) one finds, near the vein, chloritic-limestone rock; whereas where the diorite was less fissured, its decomposition must have been no less intensive: carbonates are already absent here, and pyritization is less significant.

3) It seems to me that diorite cannot be regarded as the parent rock for the gold, although visible gold is often found in it, because:

a) as has already been pointed out more than once, the gold is contained everywhere in diorite that has already been altered and, moreover, always in immediate proximity to quartz;

b) the gold-bearing quartz veins also occur in other rocks;

c) it cannot be supposed that these veins obtained gold previously leached out of the diorite, since such leaching could not have taken place without leaving traces in the diorite; meanwhile, at a distance from the veins this rock appears only slightly decomposed (perhaps even merely from weathering), or else entirely fresh.

It seems to me that, just as for the majority of quartz gold-bearing veins studied up to now their genetic connection with acid rocks has been established, so for the veins of the Bogom-Darovanny and adjoining mines it will be possible to regard as the parent rock for the gold either the granite, whose massif lies to the south of the investigated area, or the quartz porphyry, which probably forms the veins in the diorite (and may also be genetically connected with the granite).

It goes without saying that all the considerations set forth concerning the genesis of the veins of the described district, being based on a very cursory study of the collected material, cannot in any way lay claim to unconditional acceptance; they are only suppositions, the thorough verification of which—in connection with elucidating the details indicated above of the geological structure of the investigated district, as well as with studying the character of alteration of the country rocks and the microstructure of the vein quartz—must constitute the task of a detailed treatment of the collected material.

Tomsk. 15 February 1909.

Geological map of the environs of the Bogom-Darovanny mine of V. Ivanitsky.
(instrumental survey by P. P. Puzanov)

Scale: 200 sazhens [[unclear: per unit of map scale]]

Legend

• boundary of the gold-bearing area
• boundary of allotments
• old workings
• shafts, stopes (with samples)
• pits
• trenches
• dip of workings
• main veins
• boundaries of zones
• granites (?) — rock map [[unclear]]
• diorites, dioritic porphyrites [[unclear: parenthetical note]]
• porphyritic diabases
• diabase porphyrites, melaphyres [[unclear]]
• metamorphosed diabase porphyrites, argillaceous schists, limestones and altered porphyrites [[unclear]]

Visible allotment and locality names on the map include:

• Bogom-Darovanny
• Ivanitsky
• Pavel-Bogdanovich
• Uspensky
• Zakharevsky
• Magnitny
• Nikolaevsky
• Dmitrievsky
• Preobrazhensky
• Svyato-Nikolsky
• Bogom-Darovanny
• Przhevalsky
• Elizavetinsky
• Konstantinovsky
• Bogoroditse-Rozhdestvensky
• Alekseevsky
• Kopyevsky [[unclear]]
• Vsemirny
• Zakharovsky
• Martynsky [[unclear]]
• Pavel-Bogdanovich
• Bogom-Darovanny
• Trapeznikovsky [[unclear]]
• Konstantinovsky
• Kadrado [[unclear]]

Visible natural-feature labels include:

• r. Serezh [[unclear: river name]]
• Sukhaya [[unclear: stream/locality name]]
• Krutaya [[unclear: stream/locality name]]

Table 2

Compiled by P. P. Dukhov.

1) Longitudinal section of the Novostatnaya adit, stage I.

2) Longitudinal section of the Novozalognaya adit, stage I.

Scale \(1/1000\).
0 5 10 15 20 25 30 sagenes.

Scale: 0, 1, 2, 3, 4, 5 sazhen.

Drawings of stopes on the western branch of the vein.

• q — quartz.
• Porphyritic, sometimes fine-grained diorite.
• Dense diorite, rich in hornblende.
• Strongly chloritized diorite.
• Chlorite–calcareous rock, i.e., schistose.
• Soft chlorite–clayey rock.
• Dense, silicified, yellowish-gray mass.
• Limestone.
• ![black symbol] — Koteldons.

Plate 3.

For the report of P. P. Pukov.

Plan of prospecting workings on the Bogodumnaya River.

Table No. 1,
from the report of mining engineer P. P. Dudkov.

Scale: 5 arshins = 1/100 sazhen.

Legend:
q — quartz.
Dotted pattern — dense pinkish-whitish rock.

Pit A.

Pit B.

Trench.

View of the vein on the southern wall
of pit B.

View of the vein on the northern wall
of pit B.

Scale: 6 arshins.

Veins in the prospecting workings at the deposit of the Bogoroditse-Rozhdestvenskii Mine.

q — quartz.
п — altered sericitic rock.
B — altered clayey slate.
C — clayey mass with fragments.
Altered — slonica.

Scale in arshins: 1 2 3 4

Northern wall in trench No. 10.

Northern wall in trench No. 9.

1. Of these, 4 p. 15 f. 16 z. were obtained chemically from 600,000 p. of slimes with a content of 2 z. 77 d.
   * Loc. cit., p. 13.
   * On the drawing (Plate 2, Fig. 1), these levels apparently correspond to the designations with the letters \(b''\) and \(c''\).
   ** Ibid.—\(d''\). ↩