some specks of mica, and large needles of black schorl.

The worthy and ingenious Patrin says, that he himself discovered that of Daouria, in the mountain Odon Tchelon, which furnished him with many topazes, and prisms of beryl of an extraordinary size. He observes, that the quartz rather forms carcases of crystals, imperfectly hexagonal, the most usual form of that substance: and he regards that of Scotland as of a different crystallisation, the felspar appearing to have been formed in rhomboidal prisms, while the intervals have been filled with a quartzose fluid, bearing no evidence of crystallisation.

Description.

Ultramarine.

NOME V. LAZULITE ROCK.

Of this magnificent and interesting object, a better account cannot be given than in the words of Patrin.

"The Lapis lazuli, often simply called lapis, is a rock of a beautiful sapphire blue, generally mingled with veins and spots: it sometimes contains pyrites, which was formerly mistaken for grains of gold; and spangles of mica, in greater or smaller quantity. This rock is hard: the blue parts are quartzose, and strike fire with the steel; the white veins are of felsite, sometimes mixed with calcareous spar or gypsum; in some parts are to be perceived, in the tissue of the substance, brilliant plates like those of hornblende.

"The Lapis, which abounds with the blue substance, is wrought into various trinkets and other ornaments; although granular, it is capable of receiving a very fine polish.

"A valuable colour for painting is prepared from the Lapis, known by the name of Ultramarine; because it is brought from the trading towns of the Levant. The blue colour is very vivid and intense; and, above all, possesses the

inestimable property of being unalterable. It is to the ultramarine that we are indebted for those rich tints, so much admired in the skies and draperies of the first masters.

"The Lapis is found in several countries, but in very small quantities; that which furnishes the most is Great Bucharia; it is from thence that it was brought to Russia, where it was so profusely used to ornament the marble palace, which Catherine the Second built at Petersburg, for Orlof, her favourite. There are in this palace some apartments entirely lined with lapis. I would be scarcely possible to imagine a decoration more simple, and at the same time more magnificent.

"I met with, at Ekaterinburg in Siberia, a dealer in stones, who had been at Bucharia: I inquired of him concerning the nature of the mountains, whence the Lapis is brought*. He informed me that it was found in granite; that it did not run in veins or streaks, but was disseminated in the entire mass of the rock, in all sorts of proportions; that here only a few slight bluish spots were perceivable upon a rock generally grey; there the spots were closer, and of a more lively tinge: in fine, small masses were

It is said to be found near Kalab and Budnesh, in Bucharia.-P.

Site.

found of an almost entire blue; but that it was extremely rare to discover pieces as large as one's head, in which the blue should generally predominate over the white and the grey. As those blocks, which I had seen, appeared to me rolled, I asked if they had been found in the beds of rivers; and was informed they were taken from the quarry, and that they were rounded by their friction against each other in the carriage; but that sometimes, however, they were found by chance in torrents, and these were of the most brilliant blue.

"Laxmann, an academician of Petersburg, who resided several years in Eastern Siberia, said he found rolled blocks of lapis upon the shore of the lake Baikal, in a kind of gulf, to the southward, called Koultouk; but that he in vain sought for the mountain from which these blocks had been detached, and that he could get no information from the Buret Tartars, who inhabit this savage country. I have a specimen of this lapis, which is exactly similar to that of Bucharia.

"Boetius de Boot has given a long account of the manner of preparing ultramarine. This operation consists chiefly in the repeated calcination of the lapis, and plunging it in vinegar: he adds, that the oftener these calcinations are repeated, the finer the colour. That of the first

quality was sold, in his time, at 20 dollars an ounce, which is dearer than gold.

"Dufay, of the Academy of Sciences, has found the lapis when exposed to the sun, and afterwards brought into the dark, to give a phosphoric light; and that the purer and deeper the blue, the stronger the phosphorescence. grey and white kinds have not this effect.

The

"In some mineralogical systems, lapis was classed with zeolite; but a further knowledge of the nature of these two substances, has again separated them.

"The lapis has sometimes been confounded with the Armenian stone, which is totally different, and is nothing more than a fine mountain blue, or oxyd of copper; and the colour which is extracted from it, though fine at first, has not the durability of ultramarine.

"The analysis of lapis lazuli yielded to Klaproth :