19211 



NATURAL SCIENCES OF PHILADELPHIA 



187 



cased in finely fibrous actinolite was found. The most important 

 mine, however, was that at Laurel Creek, Rabun County, which 

 occurred near the contact of peridotite and gneiss. 



North Carolina: The corundum deposits of North CaroHna 

 have been described in detail by Joseph Hyde Pratt and J. Volney 

 Lewis. ^1 They occur largely in areas of peridotites and pyroxeni- 

 tes intrusive in the gneisses and schists in the mountain belt ex- 

 tending from Georgia through Clay, Macon, Transylvania, Jackson, 

 Haywood, Buncombe, Madison, Yancey, and Mitchell Counties. 

 The peridotites are usually dunite or saxonite, but secondary ser- 

 pentine, talc, chlorite, and amphibole schists occur. 





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Fig. 11. — Ideal section of a border vein of corundum at the Corundum Hill 

 mine, Macon County, N. C. (Pratt and Lewis) ; (a) gneiss, hornblendic or 

 micaceous, unaltered: (b) gneiss, decomposed: (c) yellowish vermiculites, 

 often merging into (d), and sometimes absent; (d) green chlorites of vary- 

 ing thickness; (e) the corundum vein consisting of chlorite and corundum, 

 often wdth some vermiculites; (f) green chlorites; (g) enstatite, in places 

 hard and compact, usually merging into (h) ; (h) talcose rock, usually fibrous; 

 (i) a seam of yellowish clay often carrying masses of quartz and chalcedony, 

 sometimes absent; (j) more or less altered dunite; (k) fresh dunite. An im- 

 portant variation is the development of a zone of corundum-bearing plagio- 

 clase either in the conmduro-bearing zone of chlorites or vermiculites (e) 

 or entirely replacing this zone. 



Two types of corundum veins were recognized by Pratt and Lew- 

 is: the peripheral or border veins at the contact of peridotite and 

 gneiss, and interior veins which occurred wholly within the peri- 



" J. Volney Lewis. N. C. Geol. Surv. Bull., 11, 1896. Joseph Hyde Pratt, U. 

 S. Geol. Surv. Bull, 180, 1901; and 269, 1906. Joseph Hyde Pratt and J. Vol- 

 ney Lewis, North Carolina Geol. Surv. I, 1905. Am. J. Sci. (4) 8: 227-231, 1899. 



