Kyanite, Sillimanite, and Andalusite Deposits of the Southeastern ...

48 KYANITE, SILLIMANITE, AND ANDALUSITE DEPOSITS, SOUTHEASTERN UNITED STATES
Hill at the north end of the anticline. Somewhat
similar garnetiferous rock containing kyanite and
sillimanite has been reported near New Canton, about
12 miles northeast of Tower Hill (Taber, 1913, p.
108).
B Vertical cross section of south
end of lens, looking north
C. Vertical cross section of north
end of lens, looking south
FIGURE 32. Longitudinal and vertical cross sections of elongate lens of
coarse massive kyanite, about 65 feet west of drill hole 5, east wall of
Willis Mountain, Buckingham County, Va.
shearing stress within a zone of tight folding, and
perhaps along the axes of minor folds. The formation
of the massive kyanite shoots was probably
contemporaneous with the development of foliation
and the system of gently dipping joints; massive
kyanite in layers a few inches thick extends along
several of the gently dipping joints.
The massive kyanite of Willis Mountain resembles
the kyanite of strategic quality found in Kenya
and seems to have similar desirable physical characteristics
when processed. Unfortunately, the total
tonnage of this variety of kyanite contained in the
elongated lenses, and the boulders scattered along
the east slope of Willis Mountain, is small.
Garnetiferous quartz-mica-feldspar schist containing
about 5 percent kyanite lies beneath the kyanite
quartzite. It is exposed at the south end of Willis
Mountain and in several prospect trenches on the
east slope of the ridge; a more feldspathic variety
was cut in drill hole 26 at the north end of the
ridge (pi. 4). The thickness and extent of this
kyanite schist cannot be determined because of the
heavy cover of talus.
Small amounts of kyanite occur in quartz-muscovite
schist and in some quartz veins about a mile
west of Willis Mountain and a mile east of the
eastern ridge. A few percent each of kyanite and
sillimanite are present in garnet-actinolite-quartz
rock in a narrow belt that extends east from Tower
WOODS MOUNTAIN AND VICINITY
Kyanite quartzite forms a ridge over 100 feet high
at Woods Mountain, about 9 miles southwest of
Willis Mountain. The kyanite quartzite is exposed
in an irregular curving pattern which evidently
represents a recumbent isoclinal anticline that has
been folded into several minor anticlines and synclines
that plunge 15° to 20° NE. (pi. 2). The
winding course of the Appomattox River just west
and south of Woods Mountain closely parallels the
outcrop pattern of the kyanite quartzite. In the
southern part of the mountain, the two parallel
belts of easterly dipping kyanite quartzite are the
limbs of the recumbent fold (pi. 2, section B-B') ;
quartzite on the east limb is not so continuous as
on the west limb. True thickness of the beds on
each limb ranges from about 15 to 40 feet for a
distance of about l 1/^ miles. The quartzite in the
crest of the fold is exposed over widths of 20 to 40
feet for a distance of about three-fourths of a mile
northeast of the junction of the limbs of the fold.
In the outcrops farthest southeast, the quartzite is
only a few feet thick. Strong linear structures that
plunge 15° to 25° NE. are widely developed; these
consist of fold axes, foliation crinkles, fluting in
kyanite quartzite and quartz veins, and alinement
of kyanite and muscovite.
Small tight folds a fraction of an inch to several
feet across are abundant in the foliation of the kyanite
quartzite at Woods Mountain. The characteristics
of these minor folds suggest that folds of
two ages are present, an older group formed in
the early stages of anticlinal development (fig.
33#, C), and a younger group formed during folding
of the compressed recumbent anticline (fig.
33A,Z>).
Much of the rock is gneissic kyanite quartzite
containing thin layers of coarse granular quartz,
similar to the rock at Willis Mountain. Some of
the rock has abundant large muscovite flakes, and
is heavily stained with limonite. Layers of massive
coarse barren quartzite, as much as 10 feet thick,
are present; this barren quartzite weathers to
smooth rounded surfaces in contrast to the very
rough surfaces of the kyanite-bearing rock. Grab
samples were taken of the kyanite quartzite at intervals
of about 3 to 5 feet apart stratigraphically