ECONOMICAL GEOLOGY. 
237 
The ore is granular magnetite, and is every where titan iferous. It is 
usually rather coarsegrained and frequently associated with crystals of 
chlorite in small seams and scattered bunches. The ore is in the form of 
beds, which partake of all the foldings and fractures and irregularities of 
bedding to be expected in a region where only the oldest metamorphic 
rocks are found. The deposits lie along, and just west of the line of junc- 
tion of what is provisionally set down as the lower and upper Laurentian 
series of granitic rocks, as marked on the map. It may be here noted 
that in coloring the map, this line was placed a little too far north in this 
region. There is a second, but much more interrupted range of ore par- 
allel to the one just described, and lying a few miles to the northwest. 
I visited this region in 1871, in company with Dr. F. A. Genth, who 
was at that time Chemist and Mineralogist to the Survey. 
The entire range was taken into the tour, and specimens carefully se- 
lected from many points by Dr. G. for analysis, so as to ascertain the 
average character, as well as to eliminate the local peculiarities of the 
beds. Fortunately, an association of Pennsylvania capitalists, the North 
Carolina Centre Iron and Mining Company, had invested largely along 
this range of ores, and had recently had the beds opened by trenching, at 
a great many points, so as to expose very well the general features of the 
deposits. And still more fortunately, the Company had procured the 
services of Dr. J. P. Lesley, now the Director of the Pennsylvania Geo- 
logical Survey ; and this distinguished Geologist had recently made a very 
careful study of the whole range, in all its bearings. 1 have before me 
his report, and shall give some of the more important points of his re- 
sults. I owe it to the courtesy of the Philosophical Society of Philadel- 
phia, of which Dr. Lesley is Secretary, that I am able to use the plates also, 
which were engraved for the illustration of his very elaborate and valua- 
ble report. Whatever is found below on the subject of this range of ores, 
in quotation marks, is taken from this report, unless it is otherwise stated. 
It is questioned by many geologists whether all our North Carolina 
metamorphic rocks are not altered Silurian and Devonian, like most of 
those of New England. I am glad to have the support of so eminent an 
authority in the view presented in the map published some two years ago 
and maintained in this report, that these azoic and crystalline rocks of 
Middle North Carolina are Archaean of the most ancient type and date. 
“ This part of North Carolina is occupied by some of the oldest rocks 
known ; the same rocks which hold the iron ore beds of Harford county, 
Maryland, and Chester county, Pennsylvania, and the gold ores of Georgia, 
North Carolina, Virginia and Canada. The gold mines of Guilford 
county, N. C., are opened alongside of, and not more than ten or twelve 
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