A great part of the Altaï chain is unknown to Europeans; the innumerable branches that penetrate the Chinese empire are completely so: those belonging to Russia abound in a great variety of precious and rare metals and minerals—silver, copper, and iron. In the Yablonnoi range, and other parts, there are whole mountains of porphyry, with red and green jasper; coal is also found; and in a branch of the Altaï between the rivers Obi and Yennissei there are mines of coal which, having been set on fire by lightning, have continued to burn for more than a century. The Siberian mountains far surpass the Andes in the richness of their gold mines. The eastern flank of the Ural chain, and some of the northern spurs of the Altaï, have furnished a vast quantity of gold, but a region as large as France has lately been discovered in Siberia covered with the richest gold alluvium, lying above rocks abounding in that precious metal. The mines of the Ural and Altaï are situated principally in metamorphic rocks, adjacent to the greenstones, syenites, and serpentines that have caused their change; and as the same formation prevails throughout the greater part of the Altaï and Aldan chains almost to Kamtchatka, there is every reason to believe that the whole of that vast region is auriferous: besides, as many of the northern offsets of the Altaï are particularly rich, it may be concluded that the southern branches in the Chinese empire are equally so. Thus, Southern Siberia and Chinese Tartary form an auriferous district, probably greater in area than all Europe, which extends even to our dominions in Hindostan, where the formations containing gold are unexplored.[31] The sedimentary deposits in this extensive mountain-range are more ancient than the granite, syenite, and porphyries: consequently these igneous rocks have not here formed part of the original crust of the globe. Rocks of the Palæozoic series occupy the greater part of the Altaï, and probably there are none more modern. There are no volcanic rocks, properly speaking, ancient or modern, west of the Yenissei, but they abound to the east of that river, even to Kamtchatka, which is full of them. The physical characters and the fossil remains of this extensive mountain system have little relation with the geological formations of Europe and America. Eastern Siberia seems even to form an insulated district by itself, and that part between the town of Yakoutzk and the mouth of the Lena appears to have been raised at a later period than the part of Siberia stretching westward to the Sayansk mountains; moreover, the elevation of the western part of the Altaï was probably contemporaneous with that of the Ural mountains.[32] On the whole, the chains in the direction of parallels of latitude in the Old Continent are much more numerous and extensive than those in the meridians; and as they lie chiefly towards the equator, the internal forces that raised them were probably modified by the rotation of the earth.