the Peridotites in North Carolina. 53 



the requisite amount of silicic acid and bases, had again crys- 

 tallized as corundum." 



In an article on corundum and its associated rocks, C. D. 

 Smith* points out the facts that led to his belief in the igneous 

 origin of the peridotites, but does not discuss the same. He 

 calls attention to the occurrence of corundum chiefly in chlor- 

 ite veins and says " the chlorite seems to have been first crys- 

 tallized, and then, the alumina of which the corundum is 

 composed was evidently in a state of solution and must have 

 permeated the chlorite either in thermal waters or steam." 

 The only points given to sustain this theory are that plates or 

 scales are sometimes enclosed in the corundum and that corun- 

 dum has been observed that conforms in its faces and general 

 shapes to the chlorite that is present. The other points bear- 

 ing on the origin of the corundum that he undoubtedly had in 

 mind he makes no mention of in his article. Dr. Smith also 

 states that he found " chrysolite attached as an enveloping 

 matter to considerable masses of corundum." He makes, 

 however, apparently no further mention of this occurrence in 

 any of his writings. 



In a description of the " Jenks Corundum Mine," Dr. E. 

 W. Raymondf calls attention to the occurrence of transparent 

 nodules of corundum in a matrix of the same mineral, and 

 also of the great variation in the appearance of the corundum 

 from the different veins. One of the veins has produced more 

 of the gem material, while it contains but few large masses of 

 the corundum. 



Julian, in his paper already cited, considered the corundum 

 in all cases a secondary or alteration product, and explains all 

 the phenomena of alteration in the veins by the introduction 

 of a solution of soda and alumina into the fissures, during the 

 period of alteration and metamorphism, believing at the time 

 that the dunite was of sedimentary origin. 



In an article commenting on Julian's;}; theory regarding the 

 origin of the peridotites referred to above, Wadsworth.^ in 

 speaking of the corundum, says that the corundum is looked 

 upon as a secondary mineral, and not as Genth held, the prim- 

 ary material from which many minerals originated. 



Chatard|| made a very careful chemical study of the material 

 collected across the contact between the gneiss and dunite at 

 Corundum Hill. He points out as a result of his chemical 

 analyses, that starting from the gneiss there is a progressive 



* Report of N. C. G-eol. Survey, vol. i, p. 91, 1875. 



\ Trans. Am. lust, of Min. Engrs., vol. vii, p. 89, 1879. 



\ Nat. Hist. Soc. Bost., xxii, 141-149, 1882. 



§ Science, iii, 1884. p. 4SG. 



|| U. S". Geol. Survey, Bulletin 42, pp. 45-63. 



