b CONTENTS AND ILLUSTRATIONS. 
Page. 
Plate I. General map of corundum localities in the United States 27 
II. Outcrop of peridotite at Buck Creek, Clay County, N. C . 28 
III. ^4, Corundum in chlorite at Corundum Hill, North Carolina; B, 
Corundum in gneiss, Muskrat Fork, Clay County, N. C 52 
IV. A, Bed of ruby-bearing gravel at Caler Fork, Co wee Valley, 
North Carolina; B, Ruby mine at Cowee Valley, North Car- 
olina . . 60 
V. Ruby crystals from Cowee Valley, North Carolina 102 
VI. Map showing location of Montana sapphire deposits _ _ . _ 106 
VII. -4, General appearance of sapphire district near Yogo Gulch, 
Montana; B, Face of dike in open cut 112 
VIII. Sapphire crystals from Yogo Gulch, Fergus County, Mont 114 
IX. General view of the peridotite formation at Corundum Hill, 
North Carolina 116 
X. The Big vein between the peridotite and the gneiss at Corundum 
Hill. Macon County, N. C 118 
XI. Upper end of big cut at Corundum Hill, North Carolina 118 
XII. Open cut on interior vein at the Mincey mine, Macon County, N. C_ 118 
XIII. .4, General view of the Buck Creek corundum mine, and peri- 
dotite formation. Clay County, N. C; B, Interior vein of co- 
rundum in the peridotite formation at Buck Creek, Clay County, 
N. C - 120 
XIV. Corundum deposit of the North Carolina Corundum' Company, 
Buck Creek, Clay County, N. C 122 
XV. Map showing location of peridotite rocks and corundum local- 
ities in North Carolina and Georgia 126 
XVI. Open cut on peridotite-gneiss contact at Laurel Creek. Georgia, 128 
XVII. A, Peridotite formation at Laurel Creek, Georgia; B, Interior 
vein of corundum at Laurel Creek, Georgia 130 
XVIII. A, Corundum mill at Cullasagee, Macon County, N. C; B, Inte- 
rior view of corundum mill at Cullasagee, Macon County, N. C. 160 
Fig. 1. Corundum crystal, prism terminated by base, Cowee Valley, North 
Carolina . . 15 
2. Corundum crystal 15 
3. Pyramidal crystal of Ceylon corundum . 16 
4. Corundum crystal, India 16 
5. Corundum crystal illustrating radial lines in a basal plane extend- 
ing from center of base to edges of prism 16 
6. Ideal cross section of a corundum border vein 31 
7. Cross section of an interior vein at a shaft near southern part of 
Corundum Hill, North Carolina 32 
8. Corundum crystal inclosed in granular dunite, Egypt mine, Yancey 
County, N. C , 33 
9. Map of the Buck Creek peridotite area, showing the relation of the 
amphibolite dikes 36 
10. Mass of corundum in amphibolite from Buck Creek, North Carolina- 37 
11. Ideal vertical cross section of corundum in amphibolite at Hunters, 
Iredell County, N. C 38 
12. Ideal vertical cross section of mass of peridotite soon after its in- 
trusion into gneiss 83 
13. Ideal vertical cross section showing a somewhat gradual transition 
from corundum to peridotite 84 
14. Corundum crystal showing concentric hexagons on basal plane 105 
