the
so-called " flexible sandstone," which is sometimes found in Brazil and
in the Ural Mountains, and is generally supposed to be the matrix of
diamond crystals. The presence of this peculiar rock and the occasional
discovery of diamonds in adjacent districts have led to the idea that
the itacolumite belt of North Carolina might prove to be a valuable
diamantiferous region ; but as yet no diamonds have actually been
discovered there, and but few have been found in the loose debris of
the crystalline beds. Prof. Frederick A. Genth, of the University of
Pennsylvania, describes 1 the occurrence of the two
crystalline varieties of carbon in that State,—the graphite in beds
interstratified with mica schist or gneiss ; the diamond in the debris
of such rocks, associated with gold, zircon, garnet, monazite, and
other minerals, and after speaking of this occurrence in connection
with rocks of identical age, as a very interesting circumstance, he
says : " The diamond has not been observed in North Carolina in any
more recent strata, and in the itacolumite regions no diamonds have
ever been found, as in Brazil; from which it appears that the
itacolumite of Brazil is either simply a quartzose mica slate of
similar age with the North Carolina gneissoid rocks, or, if it be
contemporary with the North Carolina itacolumite, the diamonds were not
produced in the same but came from the older rocks, and were
redeposited with the sands resulting from the reduction to powder of
these and are now found imbedded in the same, their hardness having
prevented their destruction. Seven or eight diamonds have thus far been
found. They occur distributed over a wide area of surface in the
counties of Burke, Rutherford, Lincoln, Mecklenburg, and Franklin, and
I have no doubt if a regular search were to be made for them, they
would be more frequently found." To the counties named by Professor
Genth, must now be added McDowell, and these all form, with the
exception of Franklin, a group lying together in the line of the
general drainage of the country, southeast of the Blue Ridge. Franklin
County is far to the northeast of the others ; and any diamonds
occurring there must be derived from the disintegration of another belt
of crystalline rocks, that traverses the eastern portion of the State,
near Weldon, in Halifax County, or else have been
» Mineral Resources of North Carolina, p. 28, Philadelphia, 1871.
