ILLUSTRATIONS. 
Page. 
Plate T. Outcrop of peridotite at Buck Creek, Clay County, N. C . . 10 
IT. A, Bed of ruby-bearing gravel at Caler Fork, Cowee Valley. Ma- 
con County, N. C; B, Ruby mine at Cowee Valley. N. C. . with 
plant for washing the gravels in the foreground 40 
III. Ruby crystals from Cowee Valley, Macon County. N. C 42 
IV. Map showing location of sapphire deposits in Montana . .. 46 
V. Sapphire crystals, from Yogo Gulch. Fergus County. Mont 52 
VI. Map showing location of the peridotite rocks and corundum lo- 
calities of North Carolina and Georgia . 54 
VII. General view of the peridotite formation at Corundum Hill. Ma- 
con County, N. C . . . . . . ... . . . . 56 
VIII. The '• Big vein " at Corundum Hill, between the peridotite and 
gneiss, Macon County, N. C. ... _.. 56 
IX. Upper end of big cut at Corundum Hill mine, Macon County, 
N. C . 58 
X. Open cut on a dunite vein at the Mincey mine, Macon County, 
N.C.... 58 
XI. A, General view of the Buck Creek corundum mine and peridotite 
formation, Clay County, N. C; B, Dunite vein of corundum in 
the peridotite formation at Buck Creek, Clay County, N. C . . 60 
XII. Open cut on peridotite-gneiss contact at Laurel Creek, Georgia, 
with shaft house in foreground 64 
XIII. A, Peridotite formation at Laurel Creek, Georgia; B, Dunite vein 
of corundum at Laurel Creek, Georgia . . . . . . . 66 
XIV. A, Corundum mill at Cullasagee, Macon County, N. C. ; B. Inte- 
rior view of corundum mill at Cullasagee, Macon County, N. C . 74 
Fig. 1. Ideal cross section of a corundum contact vein at the Corundum 
Hill mine, Macon County, N. C _ 13 
2. Ideal cross section of a corundum-dunite vein at the Corundum 
Hill mine, Macon County, N. C _ - . .. .. 15 
3. Ideal vertical cross section of a mass of peridotite soon after its in- 
trusion in gneiss . . 16 
4. Ideal vertical cross section showing a somewhat gradual transition 
from corundum to peridotite . 17 
5. Map of the Buck Creek peridotite area, showing the relation of the 
amphibolite dikes . ... _ _ 22 
6. Ideal vertical cross section of corundum in amphibolite at Hunters, 
Iredell County, N. C . . 23 
7. Corundum crystal showing concentric hexagons on basal piane ... 45 
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