C U P R U M. 633

But beside all these, there are two appearances of the ore of copper, which are usu-ally treated of by authors as peculiar species of Fossils, and ranked among the Gems.The firssof these is the Lapis Lazuli or Cyanus of the Greeks; the other the Turcoise.

1. Lapis Lazuli is a .very elegant and beautiful ore of copper, of the nature of thesecond copper ore before describ’d, but differing in purity, as being much less debas’d byearth.

It is a firm and compact substance, of a moderately close texture and considerablyheavy. It is of no determinate shape or size, but is found in irregular masses from thesize of a small nut, to that of a man’s head. It is naturally of a tolerably glossyand polite surface, and in the finest pieces is of a middle, purity between that ofCrystal and Spar. It is always found naked, not covered with any coat or crust, and isin colour of a beautiful deep fkye blue in its greater part, but is always variegated witha large quantity of an opake white matter, and ornamented with a number of veins ofa fine gold colour’d Marcasite. It is capable of a fine polish, and when wrought makesa very beautiful figure. The yellow veins are very bright and glossy, and the whitehave been usually fuppos’d to be a Spar, but they are in reality a debas’d Crystal; forthey make no effervescence with Aqua Fortis any more than the blue part.

This is the description of this ore in its most perfect state, and it has two varieties,which render it yet more beautiful; the one is its having the white matter very pure andpellucid as Crystal; and the other its having the Marcasite not in form of veins, but insmall and separate distinct spots. The former of these appearances has not been ho-nour’d with any peculiar name, but the latter is the Sapphire of the antients, as I havebefore observ’d in the comments on Theophrastus. All these, however, are subject tobe more or less debas’d by extraneous foulnesies, and at times descend into the nature ofthe common blue copper ore, and sometimes the fame ore is found so pregnant in cop-per as to be of an acrid taste, and have all the properties of verdigrease; there is muchof this in the West-Indies of a beautiful deep blue, and seems transparent, which iscall’d by some, from the name of a town near which it is found, Lapis Lipis.

It is found in many parts of the world, but that of Asia is esteem’d the finest. Itsgreat use, beside the polishing as a Gem, is the making the fine blue us’d in Painting,and call’d Ultramarine. ; The Asian Lapis Lazuli affords this so fine, that it will alwaysstand ; but the blue made from the German is apt to turn green.

2, Turchesia, the Lurquoife. This is a Fossil substance which has ever been ac-counted a Gem from its fine colour, though it is in reality no other than a copper ore,and that far from one of the hardest kind.

The Turquoises, however, now known among us, are though both.owing to copperand both to the fame ore of it, of two very different kinds, and two absolutely diffe-rent bodies; the one is a mere copper ore in its natural form,which in many respects muchresembles that ore of iron call’d Hæmatites. This is the Callais of Pliny, and is foundon the sides of fissures of Stones, which contain copper in form of a botryoide efflo-rescence, either in single bubbles from the size of a pea to that of a walnut, or in con-junct clusters of these rang’d side by side, and forming large flat masses. This is but ofa soft substance, though considerably close texture, but of a naturally smooth and politesurface, so much so indeed that it is often worn without any additional polish. It is ofa very beautiful pale blue with some faint admixture of green, and when broken isusually sound to be like the Hæmatites of a striated surface, and not unfrequently com-pos’d of two or three crusts.

It will not give fire with steel.

It ferments with Aqua Fortis, and is almost entirely dissolv’d by it, and may be cal-cin’d to a pure white. This is as before observ’d very much the same sort of ore tocopper that Hæmatites is to iron.

It is produc’d in Persia, and in some other parts of the East, and is valu’d at a consi-derable price when .of a good colour.

The other Turquoise is a substance very different from this, but though it does notwholly owe its origin, it owes its colour and all that makes it taken for a Gem to cop-per ore. This is the substance call’d spotted Fossil ivory by Theophrastus and the an-tients, and is in reality ivory, or the teeth, or bones of other animals, which have lainin the earth in the neighbourhood of copper ore till they have been ting’d by it withdeep blue spots and veins; which when the whole is put into a gentle fire diffuse them-selves through the whole substance, and tinge it to the fine pale blue we see. ThereVol. I. 7 Y are