3. Hornblende mixed 'with Mica.—This is an intimate mixture of hornblende and felspar, that includes scales of mica. It occurs, in beds, in gneiss and mica slate.
VII. Serpentine.
Serpentine.— Werner. Serpentinc.—Kirwan.
Alps of Switzerland, the Pyrenees, Carrapatos in Portu gal, Bohemia, Saxony, Silesia, and many other parts of the continent of Europe.
8. Uses—The finest statuary marbles arc found in primitive mountains, and also many of the varieties used in ornamental architecture.
Primitive Gypsum.—Ifitherio this rock has not been observed to form masses or beds of considerable extent in primitive mountains. Nearly the only authentic ex ample recorded of primitive gypsum, is that given by Daubuisson, who informs us he discovered a bed of it in mica-slate, in the valley of Aostc, and near the village of Cogne.
VI. Primitive Trap.
Ur-Trap.— Werner.
Printitive•Trap.—Janzeson.
Granitelles, Trap, Corneennes.—Saussztre Trapps cimitifs.—Brochant Amphibolite.—Danbuisson.
Serpentine.—Jameson.
Serpentine.—Brochant.
I. Minerals imbedded in it.—It is to the eye a green coloured simple mountain rock, of which a description will be given in our account of Simple Minerals. It frequently contains accidental minerals, or is indetermi nately mixed with another mineral. Of the latter only one instance is known. It is the mixture of limestone and serpentine, forming what is denominated verde an tico. The accidental mixed minerals arc common talc, indurated lithomarge, steatite, common asbestus, ami anthus, mica, schiller-stone, native magnesia, magne site, meerschaum, actynolite, rock-cork, rock-wood, diallage, pyrope, opal, chrysoprase, hornstone, amethyst, quartz, and hornblende crystals.
2. Subordinate beds.—The only beds it contains are limestone and euphotide.
3. Stratification.—It is scarcely ever stratified, and when traces of stratification do appear, they arc very in distinct.
4. Metalliferous minerals —It always contains magne tic ironstone, either in imbedded grains and masses, or in small veins, and these are sometimes so considerable as to be worthy of being worked as mines. There are mines of this description in the Alps. The chromate of iron, so much valued in the arts, occurs disseminated, also in imbedded masses and in veins in this mountain-rock, in the Shetland Islands, and at Portsoy. On the continent
of Europe, in Provence, and in Stiria, and in the New World in the United States of America. With excep tion of iron, this rock contains but few metalliferous minerals ; nevertheless, near to Joachimsthal, in Bohe mia, it contains so much galena, that a mine is establish ed in it ; and in Cornwall, and in the Shetland Islands, it contains native copper.
5. Formation.—It occurs in beds and mountain masses in gneiss, mica-slate, and clay-slate.
6. Decompusition.—On exposure to the weather, its surface becomes earthy, and the colour changes from green to ochre-yellow, owing to the change of the pro toxide of iron into hydrate of iron. It resists the de stroying effects of the weather more obstinately than the gneiss, mica-slate, or clay-slate, with which it is associated, and hence peaks and other projecting forms of serpentine, are observed on the Alps rising through the softer and less durable surrounding gneiss and other rocks.
Like all other magnesian rocks, it is inimical to vege tation. The mountains of which it is composed are bare and bleak ; and this nakedness, joined to the sombre co lour, gives a dreary and monotonous aspect to most serpentine districts.
7. Geographical distribution.—It occurs in great beds in the Shetland islands, along with gneiss, mica•slute, chlorite•slate, and quartz-ruck ; in beds at Portsoy in Banffshire, along with quartz-rock, trap-rock, mica-slate, and limestone ; near Cortachie in Angushire ; in Inver nesshire, and other parts of Scotland ; and abundantly in Cornwall in England.
It is very abundant in the Alps, in beds often of enormous thickness. It also occurs in the Pyrenees, but not so frequently as in the Alps. It is frequent in the mountains of Silesia, Saxony, the Fichtelgebirge, Ste.
It is common in the mountains of the United States of America. It occurs in the mountains of Valentiana in Mexico, where it alternates with beds of sienite, pri mitive-trap, and clay-slate ; and in the island of Cuba it is associated with sienite.