As soon as we ascend the mountains, we meet with a slaty sand-stone of various compactness, as it possesses more or less iron, often forming an excellent iron ore. A variety of this iron ore has been lately turned to a good use, in the manufacture of a red paint, near Knoxville, Tennessee. Different varieties of this sandstone possess different qualities. It is converted by the inhabitants into millstones, grindstones, and whetstones. Interspersed among the sandstone of the mountains we often find very beautiful and interesting specimens of hornstones, assuming a resemblance to all the silicious stones, from the chalcedony to the jasper. In this extensive range of mountains, many other minerals exist, of which we shall treat more particularly hereafter. The limestone, slate, and sandstone, as far as the writer's knowledge extends, so to speak, _form the country_; the limestone and clay slate dipping under the sandstone. Gypsum, coal, sulphate of barytes, &c. are found in these, and we shall now speak of their localities. _Gypsum._--This valuable mineral production exists in Washington County, Virginia, 20 miles north of Abingdon, in the vicinity of Saltville. It is similar, in every respect, to the plaster of Nova Scotia, and devoted by the farmers of that part of Virginia, and Tennessee, to similar purposes. _Coal_ is said to exist in immense quantities in the Cumberland Mountain. A bed of it is wrought near Knoxville, Tennessee. It is of an excellent quality; but wood is so abundant that it is used only in forges. _Sulphate of Barytes._--This mineral is found in Bottetourt County, Virginia, near Fincastle; and in Sevier County, Tennessee. _Hard Carbonates of Lime._--Stalactitical concretions abound in all the caves so often described as existing in this country. Those of Virginia are more perfectly crystallized than those of Tennessee. Under the head of _hard carbonates_ should be mentioned an extensive bed or vein in Montgomery County in the State of Virginia, near the seat of Colonel Hancock. It appears to have been formed in a chasm, in the common limestone of the country, by a calcareous deposition which resembles, exactly, in all its characters, the calcareous concretions which are found forming in the caves of the country. The whole bed may, in fact, be regarded as a cave which has been filled up in the progress of time, by this curious process. Its width is various, from two feet to ten, or more, extending along the side of a very steep ridge, for at least 50 yards, and it is said to be continued seven miles farther. _The silicious carbonate of lime_ may be worth distinguishing from the common limestone. It is found in a bed near Colonel Hancock's, and was supposed to be gypsum. It phosphoresces beautifully; it is white, and confusedly crystalline in its structure, and much harder than the common limestone. Indeed the limestone generally, on the east of the Alleghany, is somewhat harder than that on the west.