272 GEOLOGICAL SURVEY 
This ore, therefore, yields 58 per cent of iron. It has at the works a good reputation, for the ease 
with which it is reduced, and is used at the furnaces at the ford, and at King’s Mountain. 
The magnetic ores are highly interesting, from the peculiar excellence of the iron they yield. At 
the mines, three varieties of this ore are recognised. 
1. The dark colored, dull, pulverulent variety, which is disposed to be somewhat lamellar, and 
which, though not so rich as the others, is much prized, both at the bloomery forges and blast fur- 
naces. 
2. A granular ore, which presents the appearance of masses of cemented grains, of small size and 
partly crystaline. 
3. The compact ore, which is found in beds, almost entirely free from foreign matter ; it is hard 
and tough, and has a highly metallic lustre. Fragments of this variety, when exposed on the sur- 
face, become highly magnetic. 
Of these ores it is difficult to give a correct view, for much of the talcose and silicious matter with 
which they are mixed may be separated mechanically, and ought not to be set down to the ores. 
A specimen of variety 2, from which so much of the gangue was removed as could be sus- 
pended in water, after the specimen was pulverised, yielded, 
Reroxideoturon = ees acne nee aaa eae aoe ee 86.00 
[Insoluble matter and-Magnesia,- === -2s=--+--22<<2s-50 238-28 12.00 
Manganese;----—-~- == 2-2 eee e ee ee et ee ee eee ea ee) ETAce. 
100.00 
which gives for this ore 60 per cent. of iron. I apprehend that this is about an average of what 
may be expected from 1 and 2, when at all washed. 
The next shows the composition of the compact variety. 
Peroxide of 1r0n. a= sass oe cineca sas cee HOO 
Imsoluble; matter! 3-2 ane Sencar co ateencesecsseOl0O 
Qxideof mangancse= 2.26 son eee einen oe Om 
100.00 
It contains 63 per cent. of iron. 
There is another variety of ore near the top of the hill, at People’s Creek. I unfortunately lost 
my specimens from this bed; but I am persuaded that it is largely mixed with oxide of manganese. 
The existence of manganese in an ore is desirable, when the object is the production of steel, for it 
furnishes oxygen to the carbon of the iron, and thus reduces it to the proportion for that metal. 
In extracting iron from the ore, the process is purely chemical, and rough as the whole may 
seem, it is susceptible of the most rigorous analysis. For our purpose, it will be only necessary to state 
the general principles. To separate the iron from the oxygen, and the impurities, which consist of 
silica, alumina, and magnesia, other substances are placed in the furnace, with which these form 
new combinations, leaving the iron free to fall to the bottom of the furnace, or hearth, by its greater 
specific gravity, whence it is drawn off, in the form of pig iron. 'The substances thus used are 
charcoal and lime, or other ingredient that serves as a flux. 
The carbon of the charcoal unites with the oxygen of the ore and passes off, us carbonic acid, 
while the lime unites with the silica and alumina, which, by themselves, are infusible, and pro- 
duces a glassy slag, which floats on the fused iron, and is drawn off. There are other combina- 
