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

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KYANITE, SILLIMANITE, AND ANDALUSITE DEPOSITS, SOUTHEASTERN UNITED STATES
and 7.5 percent kyanite in comparison with an average
of 10 to 11 percent kyanite in the early years
of operation.
The channel samples taken in the quarries by
Chute, and from surface exposures by Mattson in
1929, provide excellent information about the distribution
of kyanite in the gneiss here. These
analyses are indicated on plate 6, and are summarized
in table 9, which shows the distribution
of samples in groups according to their kyanite
content.
TABLE 9. Distribution of kyanite in samples of kyanite gneiss
from Yancey Cyanite Co. property
Range in kyanite content
(percent)
0- 3.9. ..............
4- 6.9. ..............
7- 9.9. ..............
10-12.9. ..............
13-17.9. ..............
Percent of samples per grade group
Chute's samples '
(106 total)
1.9
9.4
42.5
30.2
16.0
Mattson's samples
(101 total)
13.9
21.8
17.8
29.7
16.8
1 The amount of kyanite in these samples was determined by heavy-mineral
separation methods by R. L. Smith and Roswell Miller III, of the U.S. Geological
Survey.
The grade distribution of Chute's samples is not
strictly comparable with that of Mattson's samples,
because Chute's samples were not of uniform length
(they ranged from 1.0 to 6.8 ft long), whereas
Mattson's samples were all of the same length (2
ft). Nevertheless, it will be noted that in each group
about 16 percent of the samples contain between
13 and 17.9 percent kyanite and about 30 percent
contain between 10 and 12.9 percent. However, a
much larger pecentage of Chute's samples (42.5 percent)
falls into the 7- to 9.9-percent range than do
Mattson's samples (17.8 percent). Probably one
reason for the difference in this grade range is the
fact that Chute's samples were all taken in the
quarries, whereas 38 of Mattson's samples were
taken from an exposure of lower grade kyanite
gneiss to the west of quarry 1.
The amount of garnet in Chute's samples does not
range so widely as the kyanite. Garnet content in
about 89 percent of the samples ranges from 7 to
12 percent, 6 whereas the kyanite content in about
89 percent of the samples ranges from 7 to 18
percent.
Chute (1944) estimated the reserves of highgrade
ore that might be mined by selective methods.
Reserves were calculated for zones more than
6 Determined by R. L. Smith and Roswell Miller III.
10 feet thick that carried 12 percent kyanite or
better. It was assumed that such ore could be projected
50 feet each way along the strike and 50 feet
downdip; no allowance was made for pillars that
might be left in underground mining. Five zones
of kyanite gneiss that contained 106,474 tons of indicated
ore having an average content of 12.5 percent
kyanite were outlined. Very little of this ore
was mined between the time of Chute's investigation
in December 1943 and the shutdown of the mine in
January 1944.
Brobst (written communication, July 1953) has
estimated that there are about 300 million tons of
kyanite gneiss having an average content of 10
percent kyanite to a depth of 50 feet in the northern
part of the Burnsville-Swannanoa district. The kyanite
content may be less than 10 percent, however,
to judge from the record of kyanite mining at Celo
Mountain and the samples of kyanite gneiss from
there (table 9).
RUTHERFORD COUNTY
Kyanite-quartz rock occurs southeast of Youngs
Mountain, Rutherford County, in an area extending
about half a mile east from the gravel road skirting
the east side of the mountain. The locality lies
about 5 miles northeast of the town of Lake Lure,
and about 3 miles by gravel road north from U. S.
Highways 64-74. The geology of about half a
square mile in the vicinity of the deposits was
mapped.(fig. 40) by P. K. Theobald, Jr., and J. W.
Whitlow, of the Geological Survey.
The principal rocks in the vicinity of the kyanite
deposits are garnetiferous muscovite schist and biotite-quartz
schist which contains few garnets. Biotite
granite gneiss occurs here also, but is more
widespread to the west where it underlies the main
ridge of Youngs Mountain. Fine-grained hornblende
gneiss is found in several small bodies in the
kyanite area, and occurs in abundance to the north.
Kyanite occurs as very fine grained white
fibrous needles in coarse gneissic white quartz rock,
accompanied by small shreds of muscovite and tiny
rutile grains; the rock has a strong linear structure.
The kyanite crystals are so fine grained and needlelike
that they resemble sillimanite in the hand specimen,
but microscopic examination shows that they
are nearly all kyanite with only a very minor
amount of sillimanite. The content of kyanite was
about 29 percent in 1 thin section examined and 58
percent in another. Coarse blue bladed kyanite is
also found in pegmatite lenses. The kyanite-bearing
rock occurs mainly as float within the area