Rocky Mountains. 423 



RECAriTULATION. 



The Ozark mountains extend from the sources of the Rio 

 Colorado of Texas, on the southwest, to the confluence of 

 the Mississippi, and Missouri in the northeast; and are con- 

 tinued in a low range from this point towards lake Superior. 

 They are widest in the southwest, and in that quarter they 

 mingle with some low tracts of secondary sandstone, extend- 

 ing froip near the gulf of Mexico to the base of the eastern- 

 most ridge of the Rocky Mountains. Whether any similar 

 expansion exists at the northern extremity, or whether this 

 range is connected as a spur to the great primitive chain sup- 

 posed to occupy the region north of the great lakes, and is 



fracture earthy. Its external colour is browuish red; its streak, and pow- 

 der blood red. This variety of ore produces good iron, and yields from 

 sixty to eighty per cent. 



Heinatitic Brown Oxide of Ij'oji. — This variety of iron ore occurs in 

 considerable quantity in the vicinity of the vein of fluate of lime, near 

 ShawaneetowD, Illinois. It occurs there under a number of imitative 

 forms, such as tabular, stalactitical, nodular, botrj'oidal, and rciiiform. 

 Its colour is blackish and yellow-brown; it is easily fused and will produce 

 near sixty per cent, of good malleable iron. 



Argillaceous Oxide of Iron. — This variety of iron ore is abundant in the 

 western parts of Pennsylvania, and Virginia, and in Kentucky, where it is 

 almost the only ore of iron that is worked. The principal furnaces in Penn- 

 sylvania, are in Cumberland, Northumberland and Centre counties, and 

 on the Juniata river. 



Columnar Argillaceous Oxide of Iron. — Near the confluence of the 

 Ohio and Tennessee rivers, is a locality of argillaceous oxide of iron. It 

 is of a columnar structure, and rises from the surface of the ground in 

 such a manner as to have some resemblance to cypress knees. This mi- 

 neral has by many, been thought of volcanic origin, at least that the cause 

 of its peculiar form is in some measure connected with the operation of 

 volcanic causes (James). 



Sulphurelof Lead, or Galena. — This mineral is abundant in Missouri 

 territory, about sixty miles southwest of St. Louis; but as I had not an op- 

 portunity of visiting the mines, I cannot say any thing respecting its geo- 

 logical situation or quantity. There are two reservations for lead, in the 

 vicinity of the United States saline, Is. From external appearances I 

 should judge the ore was abundant; but from the success of former dig- 

 gings, and the situation of the ore, which has not as yet been found there 

 either in beds or veins; but sparingly diffused in small masses, attached 

 to the fluate of lime, not exceeding in weight two or three pounds; I think 

 the quantity is inconsiderable! Every specimenof sulphuretof lead that 

 I saw there, possessed a crystalline form. 



Sulphuret of Zinc, or Blende. — Fifteen miles south of Shawaneelown 

 reniform masses of argillaceous iron ore inclosed in concentric layers of 

 slate clay, are found in a bed of slate clay. In the argillaceous iron ore 

 small particles of sulphuret of zinc occur. This is the only locality west 

 of the Alleghany mountains that I have seen of this ore. 



