William Phillips

“ Veins of tin adhere very often to the walls of the lode, by the rock which encloses them; they are always divided by other veins, and never divide them. Tin therefore seems to be one of the metals of the oldest formation: it is accompanied by substances which belong to the same age, such as wolfram, arsenicated iron, topaz, quartz, fluated lime, phosphated lime, hornblende, green and black mica, chlorite, &c. ”

“ If it should be thought that it is assuming too much, to differ from authors so distinguished as the Abbé Haüy and the Count de Bournon, I beg to offer the same apology as was offered by the latter for differing from the former in the same respects. “The attainment of truth is the great object that every man 'ought to propose to himself, who has any pretension to science.” ”

“ Enough has been said in the preceding pages of the uncertainties attending the pursuit of the miner, to amount to evidence that skill and ingenuity are often exerted in vain:—all they can do is to determine on, and put in practice the speediest and most effectual methods of ascertaining the value of a vein, at the least expense. When assisted by the best experience, they are utterly unable to form a conjecture, grounded on reasonable certainty, that the great expenses attending the trial of a vein will be repaid. ”

“ The occasional notice of what appear to be perfect cubes, added to the certainty that cleavages are practicable parallel with every plane of that solid, at first tempted me to presume that it ought to be considered as the primitive form; but the consideration of some circumstances connected with the crystallization of this substance, induced me wholly to abandon the idea. The inspection of the annexed drawings will evince that, of the five modifications described, the first alone is compatible with the cube. ”

“ It is traversed in various directions by minute veins of chlorite, occasionally embedding yellow copper ore and oxyd of tin. It is hard; scratches glass easily; its fracture is shattery and splintery. Its general colour is purplish; it is transparent at the edges, and the fragments are very transparent; a thin piece held for a short time in the flame of a candle, emits a brilliant green light, which becomes very brilliant by placing it on a live coal, from which, if it be taken at about the height of its light, it may be repeated, though with diminished effect ”

“ The fracture of the crystals, particularly of the more translucent ones, is very smooth and inclines to conchoidal; but is frequently uneven, and inclining to shattery, in those of a darker hue. I have met with some octohedrons that admitted a fracture in the direction of their faces, but have not found any of a cubical form in which a division parallel to the circumscribing planes was practicable.
The form of the primitive crystal, according to Haüy, is the regular octahedron (fig. 1.) ”

“ The total ignorance of almost every thing relating to the sciences of geology and mineralogy, and above all of chemistry, in the conductors of mines, and their agents, is not only matter of regret, but it can scarcely be doubted, is also the cause of much loss to the adventurers in mines, to the lords of the soil, and to the buyers of the ore. ”

“ All the crystals represented in the accompanying series which are so remarkably flat as to have the appearance of mere laminæ, are from Tol Carn mine, which yielded only such as are of that description, while on the other hand, the greater part of those from Tin Croft mine nearly approach in height the dimension of the cube, or exceed it. A considerable proportion of such as are rather less than that dimension exhibit no striæ on the lateral planes, which are very splendent: many of those which are deeply striated on these planes are iridescent on the surface. ”

“ With Blende on quartz, from St. Agness.
In Mispickel—with mispickel on schist.
In Wolfram—with wolfram and dark brown gossan—with woltram and chlorite from Pednandrae mine—with the primitive crystal of wolfram, mispickel and yellow copper ore, from Huel Fanny. The science of mineralogy is so intimately connected with some branches of the mathematics, that he who pretends to the former, unassisted by a knowledge of the latter, may perhaps be considered as pursuing it rather as an amusement, than as an object of scientific research. I confess myself to be exactly so circumstanced. ”

“ It has sometimes happened that in a large load, and where it is largest, the miner has suddenly arrived at a piece of dead ground in the middle of it, which in depth spreads wider so as to occupy nearly the whole of the vein, leaving on each side only a small connecting string of ore. This has been known to extend many fathoms in length and depth, and from its being narrow above and widening below, it has obtained from the miner the name of a horse. ”

“ In almost every flattish crystal of considerable dimension its natural joints are apparent when holding it between the eye and the light. If not, a slight blow will cause them to appear; and if by design or accident, the crystal fall flat upon the floor, it immediately breaks parallel with some of the planes of the primitive form and frequently even into the form itself, which is, a right prism with rhombic bases. It follows that a substance whose laminæ are held together by so slight a crystalline polarity, may be cleaved or split by various means ”

“ The only mine in Cornwall which until within the last few years was known to have yielded the oxyd of uranium, was that called Carharack, which was situated about two miles nearly south of St. Die. The crystals on a specimen from that mine in my possession are tabular, of a green colour and transparent, except such of them as are partially or wholly coated by a deposition of an ochreous substance, similar to that termed gossan by the miner. This substance also is interposed between an aggregated quartz tinged with iron, and the crystals ”

“ Cornwall is justly celebrated not only for its inexhaustible stores of this valuable substance, but for the superior quality of the substance itself; for, according to Klaproth, it is purer than that of Bohemia and Saxony, as it contains both less iron and less arsenic: and although the oxyd of tin is or has been found in almost every district of Cornwall, it is nevertheless one of those substances which are the least abundantly dispersed throughout the globe. [2] Many considerable countries are entirely without it ”

“ The ancient mode of shoding for tin-veins, consisted in tracing certain stones, of which tin formed a proportion considerable enough to excite attention, and found at or a little below the surface, to the vein from which they had been accidentally detached, so as to have passed in a sort of succession down the side of a hill. Another mode of seeking tin veins is by sinking pits through the superincumbent earth down to the solid rock, and driving a trench from one to another, north and south, so as to meet with every vein in the track through which it passed. ”

“ The great copper mine called North Downs, in the working of which no less a sum than £90,000 was lost, may be considered as an instance of the first, and Huel Alfred, from which a greater sum has been gained, is an instance of the second. There is scarcely one symptom on which the miner most relies that has not occasionally deceived him. It may be curious however to add some of the symptoms in favour of which the miner is greatly prejudiced. There is no one more favorable in his estimation than a gossany load. ”

“ Not only are the same crystalline forms generally apparent on each cabinet specimen, but even entire veins seem to be productive principally of the same varieties. In the tin-stone of Polgooth near St. Austle, I have rarely seen any other than minute crystals of the form of fig. 66, Pl. 18. That produced by Pednandrae, an extensive tin mine close by the town of Redruth, is almost uniformly of the macle described by fig. 208. Pl. 25. From Huel Fanny mine, which produced tin only in the shallow part of the copper vein, I have never observed any other forms than those described by figs. ”

“ Accident often occasions the discovery of veins. That of the mine called Huel Maggot, or Velenoweth in the parish of Phillack, was first seen by workmen employed in digging a trench for the foundation of a garden wall in a valley. It there consisted of a rich gossan, which in the phrase of the miner was very kindly. On driving into the hill, a few fathoms on the ‘course of the load,’ it produced abundance of sulphat of lead in well defined crystals, sometimes accompanied by the sulphuret, and sometimes deposited on the gossan, and, a little deeper, copper ore in considerable quantity. ”

“ The early discovery of iron pyrites and portions of yellow copper ore mingled with a large quantity of blende is considered a favorable omen for copper. Blende, as has already been noted, is by the miner called Black Jack; and ‘Black Jack,’ he says, ‘rides a proud horse,’ a phrase become proverbial, from blende being often found to lie above, in a vein rich in copper beneath. Vast quantities of it were found above the ore in the productive copper mine Huel Towan, as well as in that called North Bennar. The early discovery of lead is also considered a good symptom ”

“ Many tracts of the mining part of Cornwall are however so amply stored with veins in the direction of East and West, that there is little occasion to employ either of the above mentioned modes of discovery. There are comparatively but few mines which are known to have within their boundary only a single vein; in some there are 5, 6, or even 7. As the driving of an adit home to a vein is one of the first and most important tasks of the miner, he sometimes embraces the opportunity of so doing from a neighbouring valley along a cross course, or North and South vein, and for two reasons ”

“ To Captain Thomas Teague, of Redruth, an experienced and very intelligent miner, and who during many years has principally conducted the working of Tin Croft mine, I am indebted for the Section. He informed me that in some part of Dunkin's vein, granite was found on one side of it and schist on the other, and that detached masses of each substance were found both in it and in the South vein; and frequently, that where granite formed the country on each side of the vein, the masses were of schist, and vice versa. ”