Residual Kaolin Deposits of the Spruce Pine District, North Carolina
John M. Parker III, USGS, Bulletin #48, 1946
In 1946, the USGS surveyed kaolin deposits in Avery and Mitchell Counties, known as
the Spruce Pine District. The map below is of the Gusher Knob location in Avery
County (Land & Mineral Company) and the Brushy Creek area in Mitchell County
(Sibelco Corporation).
The Bulletin’s written description of the Gusher Knob deposit follows.
USGS BULLETIN # 48, PG. 32 -34
GUSHER KNOB GROUP
A number of promising kaolin-bearing areas lie southeast of Gusher Knob, extending
from three-quarters of a mile to two miles east of Ingalls (pl. 2). Though clay prospects
in this vicinity have been known for thirty years, no kaolin has yet been produced. Te
western part of the deposit was prospected in 1936 by F. L. Hess of the Bureau of
Mines and C. E. Hunter of Tennessee Valley Authority. About 80 holes were bored and
at least three shafts were sunk.
The deposits underlie gently sloping, broad-topped ridges on the northwest side of
Three Mile Creek. These ridges are the dissected remains of a sediment-capped
stream terrace lying about a hundred feet above the flat creek bottom. The overburden
of gravel, sand, and clay is only two or three feet thick at its lower edge. Farther up the
ridges it increases to more than six feet in thickness. The sediment cap thins out at still
higher altitudes and comes to an end at about 2,900 feet. Above this altitude four or
five feet of residual soil covers the clay.
The distribution of kaolinized granite was difficult to determine accurately because of the
thickness and extent of the overburden. The limit lines drawn are consequently less
certain than in most other localities. The western boundary may lie farther west than
indicated and nearly all lines are subject to revision. The western half of the area
seems to be underlain by a fair-sized granite body with some inclusions, whereas to the
east dikes with intervening septa of gneiss and schist appear to prevail. Large supplies
of kaolin are more certain in the western than the eastern parts. The amount of
inclusions is problematical but apparently large. Information is most reliable on areas 1,
2, and 3, and least so on 6.
The clay is of good average quality, in part stained with horneblende gneiss but not
unduly so. Kaolinization has been thorough, so that recoveries of 15 to 18 or perhaps
20 percent may be expected. The broad expanse of flat terrace favors a good depth of
clay and 90 feet has been reported in one place (Smith, F. E., Harris Clay Company).
Between 450,000 and 1,250,000 tons of refined kaolin are estimated to be available in
the Gusher Knob deposits.
The Gusher Knob deposits appear to be the second most favorable in the district. While
they probably would yield less total kaolin than the Spruce Pine group, they have the
advantage of compact distribution. The topographic situation is especially favorable to
deep and thorough kaolinization. The principal uncertainty lies in the areal extent and
distribution of granite and pegmatite; a large and systematic boring program is essential
to determine these facts.
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