method of dieffing Tin, we fhall explain the process for burning it. After all that can be done, Mundick is fuch a mortifying inmate, as by its communication corrupts the goodness of the Metal, and renders it harsh, brittle, and ill coloured. Many are the Lodes of pure folid Mundick, without any mixture of Tin, Copper, or Lead. It may in general be said, that Pyrite are to be met with in as many different forms and pofitions, as other Minerals are: fuch as vein-wife, when the Ore ftretches downwards, oftner floping a little, seldom quite perpendicular. Squat-wife, or in a horizontal position; that is, if not always quite level, yet hanging much, and dipping a little. (The fame as a true Lode plot) (Henckell). But as thefe Lodes of Mundick are not found to produce our Metals, after fome little trial they are not deeply enquired into, and are foon relinquished. If they were patiently funk upon, they might poffibly produce Tin or Copper in depth; and it is a general maxim among the Miners, "That a large Lode of "Mundick commonly rides a good horfe:" indeed, we know feveral inftances of very large Mundick Lodes, answering the pursuit of the concerned with abundance of Copper Ore in depth from whence many writers have maternalised this Mineral for Copper, which is baftardifing the daughter, whose real mother is Goffan; and yet Mundick does partly contain the feed or vitriolick principle of Copper, and therefore it may with propriety be termed the father, and Goffan the mother, or matrix, to fecundate the feed. : Mundick is continually forming concretions; and, perhaps, none of the Foffil kingdom will fupply us with more recent and vifible proofs of the like activity, in the fame short space of time we think, we have feen it make confiderable advances, in three or four years. Poldyfe Mine has lately furnished the curious with many fpecimens of Crystals of all fizes and shapes; particularly of an hexagonal column, terminated with hexagonal pyramids at both ends, four, fix, and eight inches long, to fix in the circumference. Some of thefe Crystals are beautifully correct and clear; others have one or two planes tinged with a brownish ochre, two or three of the planes, both columnar and pyramidal, are granulated with very minute glittering sparkles of Mundick, variegated like the rainbow; the oppofite fides are coated half an inch thick, with high bliftered incrustations like grapes; others, are totally capped with Mundick at one pyramid, and quite clear at the other; many of them fo beautiful beautiful and splendid, as to exceed the Iris, or the peacock's tail. In these incrustations, we fee the various degrees of approximation of matter fui generis; and from thence muft conclude, that those Pyritæ are modern to the Crystals upon which they are formed, in direct oppofition to thofe Mineralifts, who fay, all Metals, Minerals, and Foffils, were formed at the creation, as we now find them. "A circumftance not the leaft remark"able, is, that Ores are found upon Sinter or Dropftone, in "the fides and roofs of old Mines; a proof of their temporary "existence, and that they are not coeval with the world. In "fhort, Mundick is a thing that has grown, ftill grows at this day, and will continue to grow on Drufe, (a honey-combed Stone) fo long as the interior parts of this mass of earth are fubject to those motions and diffolutions they hitherto have "undergone." (Henckell's Pyritologia). Nevertheless we have met with one of these Coevalists, (otherwise a very sensible man) who infifted upon it, that those Mundick concretions were immediately formed at the creation, upon the Crystal, while it was in a liquefcent state; and at the fame time dense enough to fuftain, and support the ponderous Mineral, that it might not fall into, and destroy the geometrical configuration of the Crystal. We have likewife many fpecimens of Mundick, which are wholly coated over with Cryftal: and a large opaque mafs of Crystal, shall contain a very rich piece of Copper Ore in the middle of it, almoft totally impervious, till fractured by the fledge. Again, there are large rocks of Copper Ore, fometimes found, in all appearance as if they were folid; on breaking of which, a cavity is found in them, containing a loose Pyricubium, or exquifitely gloffy cube of Mundick. All these are fimiliar proofs of the doctrine, which we laid down in the first place. Another example whereof, we have in Ilva, an island adjoining unto Tuscany, full of Iron Mines, which when they have dug as hollow and as deep as they can, the circumjacent earth falls in, and fills them up again; and in the space of fifteen years at most, they work those Mines again, and thence draw out abundance of Metal, which this new earth hath been converted into, and which can be attributed to nothing but to the perpetual accumulation of this and other Minerals, (Alonzo Barba). Other Other crude Minerals of no esteem, are those of a ferruginous quality, which the Miners diftinguish by the names of Goffan, Cal, (more properly Gal) Cockle, &c. Our Goffan Lodes often produce Tin at a fhallow level in tolerable plenty; and chiefly that Goffan which is of the moft ferruginous ftamina, and we believe from thence denominated Gal, which is old Cornish British, and fignifies ruft; and being really an inferior Iron Ore, answers in name to its appearance. The Germans. call it Wolffram, and define it a kind of Manganefe. In this kind of Goffan, after the Tin is feparated from all other impurities by repeated ablutions, there remains a quantity of this mineral fubftance, Gal; which being of equal gravity, cannot be feparated from the Tin Ore by water; therefore it impoverishes the Metal, and reduces its value down to eight or nine parts of Metal for twenty of Mineral, which without this brood, fo called, might fetch twelve for twenty. Afterwards it is coveted by fome of the Smelters, to mix in their large furnaces, where it acts in conjunction with fome forts of Tin as a defirable flux; and increases, though it may depreciate, the lump of Metal. The general definition of Ochres in Cornwall, may be thus fpecified the rufty Ochre of Iron called Goffan; the green and blue Ochres of Copper, Verdigreafe; the pale yellow Ochre of Lead, of a Goffan appearance, but like Calamy; the brown and blackish yellow Ochre of Tin, called Goffan, Cal, Gal; and the red Ochre of Bifmuth. Thefe Goffans or Ochres, are commonly called the Feeders of their respective Metals ; and where they are found, the Metals are generally, and very justly fuppofed to be not far off. Cockle (the Skiorl of the Swedes, and the Schorl of the Germans; in English, Shirl) is a brown or blackish gloffy ftony matter, intermixed with Tin Ore in fpots and veins; often shining and resembling the Crystals of Tin Ore, from which by its weight, it cannot be well feparated; and in the Stone is not unfrequently mistaken for it, to the difappointment of the Tinner, when it comes to the teft of the fire. This Cockle composes a part of the most beautiful charge of our Granite or Moorftone; in which it is fo variegated with black and white Talck, that when the fun shines upon it, the beholder is dazzled with its fplendour. Talck, which is the Lapis Specularis, and has the several names of Gold and Silver Talck, Glimmer, Glift, Catfilver, and Black Black Talck, is very plenty in Moorstone as before; but of fuch fmall diameter as to be no way valuable, unlefs in the Stone, for its lucid appearance. There is another fort of Talck common to our Tin veins, a bluish Iron Ore. If Talck gets among Tin, it is a very deceitful brood, as it imitates the colour of the Tin with which it is in conjunction; and when stamped, it preserves its foliaceous laminated form, whereby the water in the buddle flips over its leafy fubftance; but if it had been more granulated or angular, the water might poffibly have more force upon it, and separate it from the Tin, on account of its peculiar levity. In this fituation, it is known among the Tinners, by the name of Clift, Glift, or Glidder. However, Talck and Cockle, feem to be of the foliaceous ftony kind, and are mentioned here only as troublesome companions with the Ore of Tin. Fourthly; Semi-metals. Hill fays, Hill fays, "The Tin Mines of "Cornwall afford great quantities of Bifmuth, though it is very little known there. This is a great mistake; for Bifmuth is very well known here, and our Tin Mines never yet afforded any quantity worth the faving. That we have Lodes. of Bifmuth, and thofe of Cobalt and Bifmuth together, is very true; but hitherto of little worth. According to the opinion of foreigners, no place exceeds Cornwall for variety and plenty of Minerals. "Beecherus refert de Cornubia, in dedicatione alphabeti fui Mineralis, fe credere nullum terrarum locum reperiri, qui minerarum multitudine et varietate antecellat." This fhews how great reafon we have to lament our ignorance in the examen of other Minerals befide those which produce Metal. If those of our county, who have leifure and ability to look into the contents and properties of our various Foffils, would employ their talents for that purpose, we should not long remain in our prefent darkness; a little time would bring to our knowledge the value and usefulness of much neglected treasure. Even ignorant pretenders to docimaftick operations, might in time blunder out some curious discoveries; and accident might effect, what prudence may not accomplish. Unfortunately for into the concealed contents of our numerous none pry Foffils; for the attention of the natives is principally engroffed by Tin and Copper. us, Bismuth in the ftate of Ore, is ufually of a bright filvery white, and of an obscurely and irregularly foliaceous structure. Sometimes it appears granulated; and at others, the granules are large, and the maffes coarse; in which cafe, every separate granule appears of a cubick form. It is fubject to fewer varia tions in its Ore, than most other Minerals; but is fometimes turned yellow by an over proportion of Sulphur; and fometimes. is very deeply tinged with the matter of common Mundick, and is often mistaken for it. (Kunkel, Boerhaave). It is eafily feparable from its Ore, and may be made pure by merely melting the Ore alone in a crucible in a moderate fire: when it is in a more impure ftate, it is procured by an addition of the reducing flux before mentioned; but if the fire be too fierce, the Bifmuth will be loft. A fmall portion of Bifmuth increases the brightnefs, hardness, and fonoroufnefs of Tin. The uses of Bismuth are, for making Pewter with Tin; for foldering fome Metals; for printers types; foils for mirrors; for anatomical injections; for imitating Silver on Wood; for purifying Gold and Silver by cupellation; and for rendering fome Metals fitter for being caft into moulds, as it increases their fufibility. Great quan When Zinc; the Ore of which is Lapis Calaminaris. tities of Tutenag were till lately imported from the Eaft-Indies; but the late Dr. Ifaac Lawfon obferving, that the flowers of Lapis Calaminaris were the fame as those of Zinc, and that its effects on Copper were also the fame with that Semi-metal, never remitted his endeavours, till he found the method of feparating pure Zinc from that Ore. Cadmia, or Lapis Calaminaris, is a fpungy fubftance, of a lax and cavernous texture, yet confiderably heavy. It is found in maffes of various and irregular figures, with rugged and uneven protuberant furfaces. moft pure and perfect, it is of a pale brownish gray colour; but its lax and fpungy textures, make it very liable to be fouled by extraneous matter, and thence it is often found yellow or reddish. It is moderately hard, but will not give fire with Steel; it will not effervefce with Aqua Fortis; and it calcines in a fmall fire to a pale red. In fact, the Ochre of it is a Goffan; and though the above defcript is the true and genuine Mineral of Zinc, yet that Semi-metal is not confined to that Ore alone, but is mixed in great abundance in its diffeminated particles among the matter of the Ores of other Metals, particularly of Lead. Mock Lead, Black Jack, and Blende of the Germans, is really a contaminated Zinc Ore, (and fome of it even very little fo) |