Chapter XI

SOURCE OF DIAMONDIFEROUS SOIL.—EXTRACT FROM MESSRS. BAIN, URE, DANA AND
OSBORNE’S GEOLOGICAL THESES.—VARIOUS THEORIES ADVANCED—NONE ENTIRELY
SATISFACTORY OR CONCLUSIVE.—THE ORIGIN OF THE PRECIOUS STONE VEILED IN
MYSTERY.

The extracts in the previous chapter, taken from the papers of the afore-mentioned mineralogists, show, there can be no doubt, that the diamondiferous soil of the diamond mines of South Africa is, for the most part, the débris of an igneous rock; but little or no idea is given how the mines became filled with the soil. Although I am unable to throw any additional light upon this very difficult subject, I nevertheless am of opinion that this chapter would be incomplete without giving a few more extracts from previous writers. I may mention, however, that scarcely a sufficient number of facts have as yet been gathered to enable geologists to offer any theory of the formation of the diamond mines that will carry conviction with it.

In a report to Col. Charles Warren, acting administrator of Griqualand West, by Mr. T. C. Kitto, a mining engineer who was then visiting the province, and who previously had some experience in Brazil, and which report was published in the local government _Gazette_ of July, 1879, he states: “I shall at once assume the Kimberley mine formation to be the result of earthquakes and volcanic agency. That the De Beers, Du Toit’s Pan, and Bulfontein belong to the same group; that the diamond deposit has been ejected from below, and that the diamonds were formed previous to their final deposition in the crater.”

Another geologist, Mr. Thos. Bain, district inspector P. W. D., “considers the numerous superficial deposits of calcareous tufa are the detritus of the tertiary deposits,” as the following quotation from Silver’s “Hand Book of South Africa” suffices to show: “In reference to the beds of clay-stone porphyry before mentioned, Mr. Bain supposes them to be the products of a vast volcano situated somewhere in the Drakensberg range, whose products spread ruin and desolation over the carboniferous forests for hundreds and thousands of square miles, and were afterward swept away by the action of water, except what yet remains of the débris in those porphyry dykes, and the greenstone tops of the multitudinous hillocks and kopjes in the region toward the north. The elevated plateaus of Hantam, Roggeveldt, Nieuweld and Sneeuwberg form its inland boundaries. This immense desert, as geology tells us, was once a great lake, bordered by an umbrageous flora, whose former existence can only now be attested by the petrified monocotyledons buried in its finely laminated slates, and whose waters were crowded with the numerous adentulous animals or the varied family of dicynodons and other saurian reptiles found in no other part of the globe.”

I give another extract from this admirable guide book of South Africa, as bearing upon this subject: “In the part of Namaqualand called Bushmanland, and which is a vast table-land about 3,000 feet above the sea, are immense deposits of what Mr. Dunn calls glacial conglomerate. These extend westward into the sovereignty (Free State), and in them in a sort of tufaceous limestone deposit seem to occur the diamond deposits which have made that region so famous.”

Dr. Ure, in his “Dictionary of Arts, Mines and Manufactures,” states: “The ground in which diamonds are found in the mines of Brazil is a solid or friable conglomerate, consisting

Dr. Ure, in his “Dictionary of Arts, Mines and Manufactures,” states: “The ground in which diamonds are found in the mines of Brazil is a solid or friable conglomerate, consisting chiefly of a ferruginous sand, which incloses fragments of various magnitude of yellow and bluish quartz, of schistose jasper, and grains of gold disseminated with ologist iron ore, all mineral matters different from those that constitute the neighboring mountains. This conglomerate, or species of pudding-stone, almost always superficial, occurs sometimes at a considerable height on the mountainous table-land.”

Dana says: “The original rock in which diamonds are found in Brazil appears to be either a kind of laminated granular quartz called itacolumite, or a ferruginous quartzose conglomerate. The itacolumite occurs in the Urals, and diamonds have been found in it, and it is also abundant in Georgia and North Carolina, where diamonds have also been found, while in India the rock is a quartzose conglomerate.”

The following extract which also bears upon the subject is from a report by Mr. C. F. Osborne, M. E. on the Knysna gold fields, and may prove both interesting and valuable, and this I have taken from a blue book of the Cape parliament of May, 1886:

“The mineral character of the rocks is in some respects peculiar, and
they differ much in reality and very much in appearance, from the
gold-bearing rocks of Australia or California, and even from those of
the Transvaal; and the average Australian digger, judging from
appearances merely, would doubtless, at first sight and without trial,
pronounce them non-auriferous.... There are several reasons why these
rocks present such a difference in appearance from those of the
gold-bearing countries I have named. One is that the principal
gold-bearing rock here is itacolumite, a rock which does not exist, or
is very sparingly developed, in Australia, the Transvaal, and in the
greater part of California, but which is abundant and characteristic
of the gold regions in Russia.”

I will not dilate upon the above extracts as to the source of the diamondiferous soil, and will pass on to the origin of the diamonds themselves. All authorities state that the diamond is intimately connected with gold and platinum, but I cannot find any record which convinces me of the diamond having been found in the matrix—that is to say, in the rock in which it was originally formed—as all the formation in which the diamond has been found appear to have been the detritus of older rocks, in which it by some means or other had become imbedded during the formation of the newer one.

In “Precious Stones and Metals,” by C. W. King, M. A., which is a very learned and exhaustive work, I find the following: “Pliny remarks that the diamond is the companion of gold, and seems only to be produced in gold itself. He is here correct, although perhaps it may be but by an accidental coincidence; for all the diamond mines, the discovery of which is recorded, have been brought to light in pursuit of alluvial gold washings.”[28] Mr. King proceeds to remark: “The British Museum, amongst the native diamonds, exhibits an octahedral diamond attached to alluvial gold; and, strange confirmation of the ancient idea as to their affinity, not only is the primary crystal of that metal also the octahedron, but also its secondary modifications exactly correspond with those of the diamond. Modern science has made no further advance toward the solution of this problem beyond that propounded as a certainty in the ancient ‘Timæus.’”

The theory of the Oriental philosophers upon this subject is thus elegantly condensed in the tetrastich of Akbar’s poet laureate, Sheik Fizee, which formed the legend on the obverse of his chief gold piece:

“The sun from whom the seven seas obtain pearls,
The _black stone_ from his rays obtains the jewel;
The mine from the correcting influence of his beams obtains gold;
And the gold is ennobled by the impression of Shah Akbar!”

It is interesting to confront the latest modern with this the most ancient explanation of the method pursued by nature in producing the diamond. Prof. Maskelyne remarks: “Of the numerous solutions of this problem one possesses peculiar interest, viz.: that considering diamonds as deposits on the cooling of fused metals (or other substances) surcharged with carbon.... Graphite, boron and silicon are formed on the cooling of aluminium surcharged with these elements; and the same elements—in other respects so closely grouped with carbon—separate in the adamantine form seen under analogous circumstances. The latter are crystallized, indeed, in different systems from the diamond, but they possess many of its characters in a remarkable degree.”

Prof. Maskelyne also observes: “Gold seems in every diamond country to be either the associate or the not distant neighbor of the diamond. In the diamond, splinters of ferruginous quartz have been found. A high antiquity, and an origin perhaps contemporaneous and not improbably connected with the geological distribution of gold in the quartz-veins, may be inferred from these facts.... In Brazil it has been traced to its rock home in the itacolumite (a micaceous quartzose schist often containing talcose minerals, and intersected by quartz-veins) and also in hornblende, also continuous with the itacolumite. But whether these are the parent rocks—or whether they are metamorphic in nature—its origin comes from an earlier state of the materials that have been transmuted by time and the play of chemical and physical forces into itacolumite and hornblende slate, we are not in a position to declare.”

“Until lately the diamond had never been traced to its matrix, but this has now been done, in at least two instances in Brazil.” The writer above quoted says: “The first was in 1839, and the rock which contained it was described by M. P. Chasseau (Bull. de l’Acad. Royale, Bruxelles, viii., 331) as _grès psammite_, a sort of sandy freestone, the locality being the Serro di Santantonio di Grammagoa.

“The discoverers of the deposit took from it many diamonds, as the rock was soft; but deeper, it became harder, and consequently more difficult to work. As many as 2,000 persons from all parts came to the place; but they dug without order or plan, and, undermining the rock, part of it fell down. They still drew a profit from breaking the fragments and extracting the diamonds. We cannot say how long this was continued. M. Chasseau’s paper was written in 1841, and the deposit in question, as far as we can learn, is only again mentioned by M. Semonosoffin in the ‘Annales des Mines,’ 1842. But we know that in 1855 Mr. T. Redington, a native of Cornwall, was employed by the Vice-President of the Province of Minas Geraes to trace the course and tributaries of the principal river of the diamond district, so as to find the rock from whence the diamond came. Amongst other localities he visited San Joao, about twenty miles north of Diamantina, and here found a vein yielding diamonds, which had for about eight years previously been wrought by the natives. This he began to work, and though the number, size and qualities of the stones found have never been made public, he was still engaged upon it only some few months since, and probably is so at this moment. No doubt these, examples will stimulate others to attempt similar discoveries.”

Says Garcias: “It seems to me quite a miracle how these gems, which might be expected to be produced in the deepest bowels of the earth, and in the space of many years, should on the contrary be generated almost on the surface of the ground, and come to perfection in an interval of two or three years, for in the mines, this year for instance, at a depth of a cubit, you will dig and find diamonds: let two years pass and mining in the same place you will again find diamonds. But it is agreed that the largest are only found under the bottom of the rock.”

It is singular that in the early days of the dry diggings the diggers used in joke to express the very same opinions as I have quoted above, for they often unearthed diamonds coated with a thin, dark mineral crust, which disguised merely the shape of the diamond, not the color and lustre. Many diamonds were lost through this. After some months, exposure, or the attrition caused in again disturbing the soil in which they had been lying, the whole or part of the coating was so rubbed off that the diamond and its lustre became exposed to the digger’s delighted gaze. Most probably the idea of the ancients, as to the growth of diamonds, originated in the same or a closely similar manner.

Dana says: “The origin of the diamond has been a subject of speculation, and it is the prevalent opinion that the carbon, like that of coal, is of vegetable origin. Some crystals have been found with black uncrystallized particles or seams within, looking like coal, and this fact has been supposed to prove their vegetable origin.”

I take the following “New facts concerning the Diamond” from the _Quarterly Journal of Science_, Oct. 1873:

“Whilst our knowledge of the modes of formation of other gems is so
rapidly advancing that the time does not seem to be very distant when
the chemist in his laboratory will be able to produce them
artificially if not in large at all events in microscopic crystals—the
origin and mode of formation of the diamond is shrouded in apparently
inexplicable mystery. It is even undecided whether the diamond is of
igneous or vegetable origin, whether its nature is mineral or organic.
Some diamonds appear to have been soft, as they are superficially
impressed by sand and crystals; others contain crystals of other
minerals, germs of plants, and fragments of vegetation. Professor
Goppert has a diamond containing dendrites, such as occurs on minerals
of aqueous origin, and there is at Berlin a diamond which contains
bodies resembling _protococcus pluvialis_, and another containing
green corpuscles linked together, closely resembling _polinogtœa
macrococca_. (Palmoglœa Micrographic Dictionary.) Sir John Herschel
quotes the case of a Bahia diamond mentioned by Harting, which
contained well-formed filaments of iron pyrites. Messrs. Sorby and
Baker have shown that the diamond may contain cavities entirely or
partially filled with a liquid, probably condensed carbonic acid, and
that the black specks in diamonds are really crystals which are
sometimes surrounded by contraction cracks, a black cross appearing
under polarised light. Sir David Brewster has likewise pointed out
that the diamond possesses strata of different reflective powers. M.
Damour states that diamonds sometimes contain spangles of gold in
their cavities.... When shielded from contact with the air, the
diamond may be exposed to the highest temperature of our furnaces
without undergoing alteration, at least in the case of the colorless
diamond; of colored diamonds more will be said hereafter.... A crystal
of diamond, inclosed in a piece of dense coke and placed in a plumbago
crucible packed with charcoal powder, was heated for half an hour in
one of Siemens’ regenerative furnaces to the temperature at which
cast-iron melts, without undergoing any change whatever. Another
diamond, a cut (rose) diamond, which was inclosed in a crucible as
before and heated for ten minutes in the furnace to a temperature at
which wrought-iron melts, retained its form and the smoothness of its
facets but became quite black and opaque, and exhibited a strong
metallic lustre. The black portion formed a distinct layer of the
thickness of a hair covering the unaltered substance within. These
results confirm those of Schrötter, and appear to justify the view
that diamond, though it undergoes no change when exposed to the
greatest heat of a porcelain furnace or that at which cast-iron melts,
is slowly converted at the temperature of molten wrought-iron into
graphite. G. Rose states that some of the specimens of diamond in the
Berlin collection appear quite black by reflected, though translucent
by transmitted light, and that this black substance lying in the
little irregularities of the surface is found by its behavior in fused
nitre to be graphite. The relative ease with which graphite and
diamond burn was determined by exposing them to the same temperature
for the same time, when the following amounts of the three specimens
were consumed:

Foliated graphite 27.45 per cent.
Diamond 97.76 „ „
Granular massive graphite 100.00 „ „

“In a superb cut diamond weighing between six and seven carats, the
brilliancy of the stone was decidedly increased after the operation.
The loss of brilliancy observed by Mr. Schrötter is a proof, in M.
Baumhauer’s opinion, that notwithstanding the precautions employed,
the diamond had come in contact with the oxygen of the air, or else
that at so elevated a temperature a reducing action had been effected
upon the magnesia (in which the diamond had been packed) by the
diamond, which had then been superficially burnt by the oxygen of that
earth.

A diamond which presented to the naked eye an appearance of dirty
green was treated in a similar manner; examination with a lens showed
that the color did not extend to the entire stone, but was confined to
small portions, which formed small green clouds in the centre of the
mass. After heating to a white heat in hydrogen, the brilliancy of the
surface remained as before; the transparency was rather increased than
diminished, but the green hue was transformed into pale yellow.
Another small diamond, of so dark a green as to approach black, and
almost opaque, assumed a violet hue, retaining, however, its
brilliancy, and becoming more translucid. A small cubic diamond of
light green color preserved its brilliancy and transparency intact,
but lost its color completely. No difference in its weight before and
after the operation could be perceived.

“Brown diamonds lose most of their color when heated to whiteness in
hydrogen; they generally assume a grayish tint, and in all cases the
shade is much lighter, and on examination with a lens they appear
limpid, with black spots. Diamonds with a yellow tint, such as Cape
diamonds almost invariably are, scarcely lose any portion of their
natural color.... Several experiments were made by von Baumhauer, in
concert with M. Daniels, upon gray diamonds, in the hope that the
effect of heat would, by removing their color, add to their value;
but, unfortunately, the desired result was not achieved, as the
diamonds presented after treatment the same grayish appearance as
before. Very different results are obtained when, instead of heating
the diamond in an atmosphere of hydrogen, it is heated in contact with
the air. It is unnecessary to employ a white heat, or to subject the
diamond to it for so long a time, in order to render it dull, and
consequently opaque; this being the result of positive combustion,
which is proved by its loss of weight after the operation.

“This combustion is, however, quite superficial, as shown by M.
Daniels, who found that when repolished the diamond recovered
completely its transparency and its water; it was, moreover, remarked
by Mr. G. Rose that if the diamond which had become dull was moistened
with essence of turpentine, it reassumed its transparency and retained
it so long as its surface continued moist. The diamond may also be
heated in an atmosphere of oxygen.... In this case the stone obtains a
vivid state of incandescence, and burns with a dazzling flame long
before the platinum crucible has attained a reddish white heat. In
most cases after the lamp has been withdrawn and the crucible is no
longer red hot, the diamond continues to burn for some time, and
presents the appearance of vivid light upon a dark ground. When the
diamond is very small combustion may even continue until it is
entirely consumed, and it is then seen to dart a more vivid flame at
the last moment, like a burning match, the instant previous to
extinction. When the stone is of considerable size the heat produced
by combustion is insufficient to maintain it after the removal of the
lamp, and it ceases in a few moments, notwithstanding the oxygen which
continues to flow into the crucible. Although this last experiment has
been repeated several times by these experimentalists, no other result
has been observed than tranquil combustion of the diamond; such
phenomena as turning black, transformation into coke, change of the
state of aggregation, bubbling up, melting or softening, rounding of
corners and angles, were in no case presented to our notice. Once only
in experimenting upon an opaque grayish diamond, a few sparks were
emitted, but these were evidently due to the presence of some foreign
elements incorporated with the whole. Neither did the diamonds burst
or split, save in one case, where such was foreseen by M. Daniels: a
stone evidently composed of two diamonds joined together, upon the
first application of heat broke with considerable violence into two
fragments, each constituting a decided crystal.... All that took place
in the crucible could be distinctly seen through the sheet of mica,
and thus ample evidence was obtained that the diamond, while in a
state of combustion, is surrounded by a small flame, the exterior
envelope of which is a violet-blue, similar to that produced by oxide
of carbon in a state of combustion.

“This is especially the case when the diamond is rather large, when
the lamp has been withdrawn and the platinum has ceased to glow; the
diamond is then seen upon the black ground of the crucible, brilliant
with vivid white light, and surrounded by a zone or aureole somewhat
less bright, its exterior edge being a blue-violet color. Some highly
interesting microscopic observations relative to the dull surface of
diamonds which have undergone partial combustion have been
communicated by Mr. G. Rose; he has discovered on them regular
triangular markings that resemble those occurring in abundance on the
fine crystals from the Vaal River, and recall the faces formed on
planes of crystals, soluble in acid, by the slow and imperfect etching
action of such a re-agent, as, for example, the action of hydrogen
chloride on calcite. Like them these depressions on the diamond bear
an exact relation to its crystalline form, and are determined by
certain definite faces, their sides being parallel to the edges of the
octahedral faces of the crystal. Measurement with the goniometer shows
them to belong to the icositetrahedron, the faces of which have not
been met with on diamond. These symmetrically shaped pits can easily
be seen by heating a thin plate of boart in a blow-pipe flame and
examining it under the microscope.

“By prolonged heating several small triangular pits will often merge
into one large one. A crystal of diamond, even when so reduced in size
by oxidation as to be only visible with difficulty, continues to
exhibit sharp edges and angles. A dodecahedron, with very rounded
faces but smooth and brilliant surface, also exhibited the triangular
pits often very distinctly; moreover, it had a brown color, which was
not destroyed by heat, and must therefore be of a totally different
nature from that of the topaz or smoky quartz.”

The above copious extracts by no means exhaust the very interesting and valuable particulars to be found in the article, and I would advise all interested in the matter to purchase this issue of the magazine, if still in print, and read for themselves.

It is a well-known fact that river diamonds and the diamonds of each mine are quite distinct in character from each other. The Old De Beer’s stones are much more like those of the river than are those of Kimberley. An experienced buyer can tell at a glance in most cases where a diamond was found, and many buyers, diggers and other experts have on oath expressed their conviction as to the source of certain stones before courts of law.

There are no rents or large fissures in the hard containing rocks of the Kimberley mine, but the joints and bedding remain undisturbed, thus showing that earthquakes have not acted upon them, at least to any appreciable extent.

There can be little doubt but that the pits or craters were formed by volcanic agency, but it does not follow that the contents thereof were thrown up at one and the same time, nor indeed that the present contents were derived from the craters at all. After denudation had taken place, calcareous tufa was deposited from the waters, and then the ferruginous red sand. It does not appear probable, as suggested by Mr. Kitto, that “the diamond was formed by a rock being crushed between other rocks previously to its being brought to the surface by volcanic agency,” as the rock would thus be merely broken into small fragments, whereas it is in the form of an impalpable powder, intimately mixed with boulders, nodules and crystals of foreign rocks.

Pl. III.
]

Had diamonds been formed in this rock, and the rock crushed, the brittle diamond would not, in my opinion, have escaped being also crushed. It seems a more feasible theory that the rock when first elevated was in a heated state, and brought into contact with water then covering the land, and the sudden cooling caused its sudden disintegration, and that the diamonds and other materials foreign to it got mixed with it subsequently. However, in either case, the diamonds and other materials contained therein would still have to be accounted for, and it does not appear probable that these should have all been formed with or within one single rock, or that they are all of the same period and were elevated at one and the same time.

If diamonds were formed by heat, it was not in the Kimberley mine, as the shale walls and the agglomerate within the mine show no signs of having there been subjected to any great heat; on the contrary, water and air seem to have been here the active agents.

From the foregoing extracts it will be seen that no theory as to the formation of the diamond hitherto advanced is completely, if at all satisfactory, and the mystery, if penetrable, must be left to the geologist of the future.

GEOLOGY, FOSSILS, ETC.
DESCRIPTION OF PLATES.

PLATE I.

FIG. 1. Scale ¹⁄₆₀ inch to the foot. This represents a section of a shaft sunk by the Kimberley Mining Board, at the N. E. of and about 700 feet from the then margin of the mine. The section was taken by Mr. Geo. Jas. Lee, a gentleman who was at one time chairman of the mining board, and who, when it finally decided to abandon the shaft named in 1878, took the section of which the accompanying diagram or illustration gives an accurate representation.

The dip of the strata is about 2°.5 N. N. W.

(_a_) Represents a heap of diamondiferous débris from the yellow ground of the mine, 14 feet in depth.

(_b_) Surface red sand, 6 feet thick. There was no calcareous tufa underlying the red sand here, as is usually the case within the mine proper and its immediate vicinity.

(_c_) Jointed trap, or blue whin, 15 feet.

(_d_) Light colored shales; bluish white, olive yellow, gray, etc., 25 feet. This layer, surrounding and joining the mine, is 50 feet thick, and contains many fossils, some of which are shown in the following plates.

(_e_) Black, or bluish black carboniferous shale, containing four or five “iron bands,” or limonite (marked _f_), from 1 inch to 1 foot thick. This layer is 225 feet thick, and in addition to many fossils also contains numerous flat-rounded pieces of black shale, of a harder nature than the body of the reef, and generally with a _septum_ dividing the nodules. Water has evidently worn the masses down on each side of this hard division, often giving them the appearance of oyster, mussel and other shells, also of fish and other forms. One such stone amongst many (marked with an arrow) was found just above the hard rock, which here commences.

(_g_) A trachyitic _breccia_ of specific gravity 2.815. This is of a very tough, horny nature, and of a pale bluish gray color, sprinkled with small particles, both angular and round, of a darker color (3 feet).

(_h_) Compact augitic, or hornblendic, very tough (8 feet).

(_i_) Seamy do. do., closely resembling basaltic trap, 4 feet worked, but of unknown depth. The total depth of the working represented in the diagram is 300 feet, and was the deepest working in the Kimberley mine at the time that it was abandoned.[29]

FIG. 2. This represents a diagrammatic section of the interior of the Kimberley mine, from the surface to a depth of about 300 feet, and made up as follows:

(_a_) Grass, etc.

(_b_) Red sand as in Fig. 1, 6 feet.

(_c_) Calcareous tufa, 6 feet.

(_d_) Yellow diamondiferous ground, 25 feet. At the junction of the “yellow” and “blue” the change of color previously alluded to is shown, and also the porous layer with water oozing from it, and trickling down the “face” of the claim.

(_e_) “Blue ground” with various “greasy seams;”

(_f_) and boulders.

PLATE II.

FIG. 1. Hind feet and portion of the vertebræ of a fossil _Dicynodont_ reptile (_Owen_), natural size. Found by Capt. Jas. Scott Helps, in the white shale in a cutting 50 feet deep, at the east of Kimberley mine, facing claim .018, and 40 feet back from the margin of the mine, measuring from the surface.

The above was drawn by Mr. Geo. Jas. Lee, in Jan. 1878, soon after it was found. The above specimen, together with three others, were presented by Mr. Geo. Jas. Lee to the trustees of the British Museum, and were, I believe, submitted to Professor Owen, who has now for some years past been engaged preparing a monogram upon the Dicynodonts. From the _Photographic News_ of Oct. 16th, 1885, I take the following: “The British Association meeting at Aberdeen. In the Geological section, Dr. R. H. Fraquair described a new and very remarkable reptile, lately found in the Elgin sandstone, entirely from a photograph of the specimen submitted to him by Professor Judd. He was able to assign the creature to the genus _Dicynodon_, which characterizes similar sandstones in South Africa.” There are no sandstones, however, near the Kimberley mine, but the casts of Dicynodons have been found both within and without the mine, and also in fragments of white shale upon the surface of the ground a few hundred yards away from the mine. In Mr. Ralph Tate’s “Historical Geology,” the following passage occurs:— “Reptiliferous Sandstones of Morayshire: Geologists have maintained, on stratigraphical grounds, that the Reptiliferous Sandstones are of the age of the Old Red Sandstone; but the intervention of a conglomerate implies a stratigraphical break, and a lapse of time of indefinite extent; and the paleontological evidence favors the supposition that these sandstones are of Triassic age.” In the light colored shales to which I allude, and nearly in the same place, a fragment of a fossil fish (_Palæoniscus_) of Triassic age was found, and was presented to the British Museum. I may here repeat a passage from Mr. W. S. Dowel’s paper, already quoted in this chapter: “Professor Liversidge describes the geological formation of the district (Bingera, 350 miles north of Sydney, Australia) as being of the Devonian or Carboniferous age, but when making a visit in 1873 he was unable, in consequence of want of time, and wet weather, to secure fossils in order to verify his opinion. Since then Mr. Donald Porter and others have discovered fossils and indications that clearly go to show that the professor was correct in the opinions he had formed respecting the nature of the geological stratification and the age to which it belonged.”

FIG. 2. Portion of a fossil leaf, natural size, found by Mr. Geo. Jas. Lee on Oct. 13th, 1880, in the white shale from the Kimberley mine, at a depth of about 50 feet, facing road 9, south. Length (as restored), 2¹⁄₂₀ inches; apex (restored), ¹⁷⁄₄₀ inch; width (entire), 1¼ inches.

I must leave it for fossil botanists to determine the name of this leaf, but should it turn out to be identical with Heer’s “_Populus primæva_” (which I believe it to be), “from the Urgonian Pattorfick, Greenland, described twelve years ago (1875) and still remains (in 1885) the sole representative of this sub-class in any formation below the cenomanian and the most ancient dicotyledon known.” It is a very valuable specimen, and almost unique, and must be a source of great satisfaction to the fortunate finder, as well as geologists in general. Unfortunately at this time I have no books of reference upon this subject by me, nor have I seen a report of Heer’s discovery, therefore I must leave the classification of the above leaf entirely in the hands of experts in fossil botany.

A photograph of the impression of the leaf has also been taken, of which Fig. 3 is a copy. An impression of the upper and under surface of the leaf was found to have been very perfectly preserved as a hollow mould when the block of shale containing it was split in halves.

PLATE III.

FIG. 1. This is a photograph of a portion of the stem of a _Sigillaria_, found in a fragment of black, or carboniferous shale, in the centre of the north margin of the Kimberley mine, at a depth of about 100 feet. This probably is a new, or at all events a hitherto undescribed species.

Other very perfect casts of _Sigillariæ_, as well as of Lepidodendra, have also been found in the black shale. In the same shale, and about the same locality, an imprint of a species of large reptile was found, probably of the order _Crocodilia_. The imprint was very perfect, and many feet in length, but unfortunately the native workmen then engaged in throwing down this “reef” had thrown down to the bottom of the mine every vestige of the fossil, before a friend of the writer requested Mr. William McHardy (then and now manager of the Central company) to procure a specimen for him. Mr. McHardy saw this cast himself and informed my friend of the find, and at his request (my friend’s) he at once returned to save it, but unfortunately not a vestige of it was to be found, the natives having thrown a vast quantity of reef down, so that the proverbial needle in the bottle of hay was easily discernible in comparison with my friend’s fossil cayman. Other interesting fossils have been found in these shales, and have been deposited by their owners in various museums in Europe and America.

This concludes an account of all the fossils in the shales of which I can give any authenticated delineation, but I may mention that dendrites are very common in the light shales, caused by iron stains, mostly of a dark red color. I have already stated in the body of the chapter relating to the Kimberley mine that coal, from a mere trace in thickness to eight or ten inches, has been found in the black shales surrounding the mine.

From the above-mentioned facts, I am inclined to believe that the exposed strata of the Kimberley mine extends from below the carboniferous in the primary rocks to the triassic in the secondary rocks, of course excluding the tufa and red sand, which would be much more recent, and from which I have not heard of any fossils being found.

PLATE IV.

FIG. 1. This shows a transverse section of a fragment of lignite found in the Kimberley mine, in Claim 165, at a depth of 140 feet, and embedded in “blue ground” or diamondiferous soil. Color, jet black.

_a.a._ Junction of two annual layers, or rings.

_b.b._ Fissure through medullary ray.

_c.c._ Portion of medullary ray.

Average of internal diameter of tubes, ¹⁄₁₀₀₀ inch.

Internal diameter of large tube, ¹⁄₈₀₀ inch. Number of layers from outside to centre of stem from which the section was taken, 48; and the remains of the bark still adhering to the specimen, ¼ inch thick. The above was drawn on Sept. 18th, 1877, by Mr. Geo. Jas. Lee, F. R. Met. Soc.; F. R. M. S., with the aid of neutral tint glass, 10 inches from the paper, and with ½ inch object glass, and A, eye piece, and magnified 121½ times, but here reduced to about 82.6 times.

The hardness of the lignite found in the Kimberley mine varies from that of soft charcoal to that of calcite, with which mineral it is mostly impregnated; the deepest being the hardest on account of containing more lime, and having undergone a greater change. It has been found in various parts of the mine, and at different depths. It has been also found in all the other mines, and in several instances large portions of stems, branches and roots were discovered. A specimen from De Beers mine was as hard as flint, but still retained its black color. In a specimen of a supposed root from De Beers mine the cells were square, instead of being circular, as in the figure.

I may here observe that “fossilized wood,” looking much like chalcedony or agate, is plentiful all over South Africa, and in the “Bush” (forest) of the Boston saw-mills, in Natal, not far from the river Umkomaas, inland to the north of Pietermaritzburg, whole stems of gigantic fossilized trees are to be found—and of the hardness of silex lying upon the ground. So far as I am aware the whole of such specimens are identical with the lignite of the Kimberley mine, thus tending to show that at one time this vast continent was/covered with forests of gigantic pine trees. The question at once arises, what has become of those forests? Have they been turned into coal in the place where they grew? or have they been washed into an ancient ocean and thus transported to some distant place? I think the answer must be that the greater portion have been washed away, and the remainder, the extent of which it is impossible to estimate, turned into coal and silicated wood, in, or nearly _in situ_. Fossil botanists will notice with interest the absence of distortion in the cells in the section delineated above, as evincing the fact that they have not been submitted to any great pressure.

Many of the specimens when found exhibited very evident signs of having been much rolled about and water worn, by their rounded ends, and the absence of attached branches, twigs, bark fruit and leaves, none of which have been found but the stems, larger branches and roots, with the exception of a portion of bark on the piece of the stem from which the above section was taken.

I must here draw the attention of my scientific readers to the great similarity to the section here depicted, and to a similar section of Greenland coal, as figured in the “Micrographic Dictionary,” 3d edition, 1875. The only apparent difference is in the slight distortion of the cells in the coal from Greenland.

FIG. 2. This shows a vertical radial section of the same lignite as that of Fig. 1, and drawn upon a slightly smaller scale, and by the same means, by Mr. Lee.

Diameter of pits or glands, rather less than ¹⁄₁₀₀₀ an inch, or ¹¹⁄₁₂ of ¹⁄₁₀₀₀ = .000916 of an inch.

Centre bright spot of gland ⅔ less than the gland.

The above section shows a single and double row of glands, by means of which Mr. W. Carruthers classifies this lignite as being derived from _recent pines_. (For Mr. Carruthers’ report and that of other authorities of the British Museum, see end of this section.) I may here state that I have seen many very beautiful sections of coal made by Mr. G. J. Lee, obtained by him from various parts of the Cape Colony and the Free State, and they all more or less show the single and double row of pit arrangement, the only difference being that the pits or glands are much smaller, as are also the tubes.

Vertical tangental sections are also the same as in the lignite, which exhibit the usual characteristics of sections of pine, in showing the usual reticulated and oval resin cells. In some sections the open network of the cells is very beautifully preserved.

The general reader would hardly thank me for further geological disquisitions, which I therefore abandon, though with a certain amount of reluctance.

FIG. 3. Remains of a shell, natural size, found by Mr. Hugh Cowan, in February, 1878, in his claim 163, imbedded in solid “blue ground,” 205 feet deep.

The color of the body of the shell is pale lavender, with white convolutions. Drawn by Mr. Lee, and presented by him to the British Museum.

It will be noticed that the above specimen was much broken and water worn. The outside of the shell was highly polished, and the broken edges much rounded.

FIG. 4. These are representations of the natural size of two bivalve shells, drawn by Mr. G. J. Lee, and found by Mr. James Beningfield in his claims 150 and 377 in the Kimberley mine.

These shells were of an olive-green color, and imbedded in fine clay sandstone. They were given by Mr. Beningfield to Mr. Lee, who presented them to the British Museum, the receipt of which was never acknowledged by the Museum authorities. I therefore fear that they have been lost.

I am not aware whether the above are marine or fresh-water shells. Several other specimens of shells have been found by Mr. James Beningfield, who has unfortunately mislaid or lost them, and I have heard of other diggers having also found specimens, but I have not had the good fortune to see them. The above were evidently found in “erratics,” but that found by Mr. Cowan was undoubtedly found in the solid diamondiferous ground.

EXTRACTS FROM GEOLOGICAL MAGAZINE.

“_Fossils from the Diamond Field, South Africa._—Mr. George J. Lee, of Kimberley, Griqualand West, has forwarded through His Excellency, Colonel Lanyon, the Governor of the colony, to Sir Joseph D. Hooker, C. B., for presentation to the British Museum, part of a carbonized[30] branch of a coniferous tree, found 195 feet below the surface in claim 196; a fragment of a fossil fish (_palæoniscus_) of Triassic age; and four casts of portions of the vertebral columns and ribs, and a foot of a small dicynodont reptile, preserved as hollow moulds, in finely laminated and friable shale. Also numerous pyritised bodies, possibly replacing some organism. The reptilian remains have been submitted to Professor Owen, C.B., who will notice them more fully hereafter. The fossil wood will be examined by Mr. W. Carruthers, F. R. S.—_Geological Magazine, April number, p. 192, Decade II., Vol. VI., 1879._”

NOTE ON MR. G. J. LEE’S SPECIMENS OF FOSSIL WOOD FROM GRIQUALAND.

“_Sir_: The lignite from Kimberley mine, claim 196, consists of stems or branches converted into a brittle lignite, which still preserves the original size and form of the stems, and exhibits the internal structure peculiar to _coniferæ_. The wood cells have a single series of discs, as in the wood of the recent pines.

“The specimens from Kimberley mine, claim 165, are more altered, and approach the condition of our Paleozoic coal. The small portions which show structure (mother coal) consist of fragments of coniferous wood, exhibiting the disciferous wood tissue with the discs in single rows. The slides from the coal of Heilbron, Vaal River, Free State, consist of wood cells, with discs in single or double and opposite rows, as in the recent pines.

“W. CARRUTHERS,
“Botanical Department, British Museum.”—_Geological Magazine, 1879, June
number, p. 286._

NOTE.—The Paleozoic coal mentioned above was found imbedded in sandstone similar to that of the shells.