32 CORUNDUM, ITS OCCURRENCE AND DISTRIBUTION. 
The line of contact betAveen the zone of alteration products and the 
gneiss was very sharj) and distinct in all the contact veins examined. 
The minerals cleA^eloped between the corundum-bearing zone and the 
dunite are in great abundance and differ from those between that zone 
and the gneiss. 
In a cross section of an interior vein at a shaft near the southern 
part of Corundum Hill, in a distance of from 20 to 25 feet, the follow- 
ing has been observed : 
1. Dunite, liard ;aid apparently unaltered. 
2. Dunite, somewhjit friable and discolored, passing into 3. 
3. Talcose rock, fibrous, merging into 4. 
4. Enstatite, grayish and somewhat fibrous. 
5. Green chlorite, (j to 15 inches in width. 
6. Green chlorite, corundum, and spinel, G to 8 feet wide. 
7. Chlorite, same as 5. 
8. Enstatite, same as 4. 
9. Talcose rock, same as 3. 
10. Dunite, same as 2. 
11. Dunite, same as 1. 
II 10 
■'7' ;'-\'— ^^^/i 'i^y.v^pfe^w ';,-:; 
Z 1 
■' ^^yic'^^mm^ii'^v^'^-'^^^^y^^y' ' 
' -' ,-/ 1 /,=i.-^:-- '^^^"^ xN /^ „ ^^ " :V:.-.-:->=s ' , V' / s \ ■ 
xM X (- ^ ''^sEE^:^=jrv-^-// J// II ^ x\ = //-=~;p:F^aE£^ ,1. , ^_ , 
_ - ;: ^^^ T^iHiftr; c ; i '; ,^yi^<l> ;; : ; . 
Fig. 7. — Cross section of an interior vein at a shaft near southern part of (Jonindum 
Hill, North Carolina. 
The similarity of the two parts of the vein separated by the corun- 
dum zone, as already described and as illustrated in fig. 7, is very 
apparent. 
Although the section just described is a special case, it was observed 
that all of the interior veins had the same character on both sides of 
the corundum-bearing zone. As has been already stated, either a 
talcose or a serpentine rock may be the limit of the cross section. In 
one of the interior veins at Corundum Hill near the west end of the 
outcrop, the zone of corundum, chlorite, and vermiculites is in direct 
contact, both on the hanging and on the foot wall, with a serpentine 
