the Peridotites in North Carolina. 65 



observations, the most important of which are the occurrence 

 of the corundum surrounded by granular dunite and also by 

 serpentine ; its occurrence with and surrounded by spinel ; the 

 sharp contact between the gneiss and the alteration products 

 of the contact-vein ; the same sequence of alteration products 

 which are found on both sides of the corundum-bearing zone 

 of a dunite-vein and which are almost identical with the du- 

 nite side of a contact-vein ; the usual narrowing and pinching 

 out of the dunite- veins, the trend of which is toward the cen- 

 ter of the mass of dunite ; while the contact-vein seems to ex- 

 tend downward indefinitely. 



The laboratory experiments of Morozewicz* and Logoriof 

 into the solubility of alumina in a molten basic glass and the 

 separating out of the corundum and spinel as the first minerals 

 when the glass began to cool, also give strong support to the 

 igneous theory of the origin of the corundum accepted by the 

 author. 



Thus the facts obtained in the field and in the laboratory 

 both point to the same conclusion regarding the origin of the 

 corundum associated with the peridotite rocks. 



In conclusion the author desires to express his thanks and 

 indebtedness to Prof. L. Y. Pirsson of the Sheffield Scientific 

 School for valuable aid in the preparation of this paper. 



N. C. Geological Survey, March, 1898. 



* Cited on p. 60. 



f Zeitschr. liir Kryst., vol. xxiv, p. 285, 1895. 



Am. Jour. Sci.— Fourth Series, Yol. YI, No. 31.— July, 1898. 

 5 



