224 Bulletin of Laboratories of Denison University. [Voi. xii 



ring near Charlotte as a true porphyry, and gave some general 

 results of a microscopical examination of thin sections of the 

 rock, including a chemical analysis. Still a third locality in 

 North Carolina where leopardite is reported to be found is re- 

 ferred to by Genth, namely, near the Steel mine m Montgom- 

 ery county. 



More recently the leopardite occurring near Charlotte has 

 been noted by Merrill' and Lewis". After briefly describing 

 the general appearance of the rock, Professor Merrill makes 

 further statement of its economic value. In connection with 

 his work on the building stones of North Carolina, Lewis visit- 

 ed the locality to the east of Charlotte, where the leopardite is 

 exposed, and, so far as contained in published accounts of the 

 rock known to me, he was the first to note its true geo- 

 logical occurrence. 



Quartz porphyries in association with other closely similar 

 acid volcanic rocks are developed, in places, over the central 

 and the northwestern parts of the state. So far as known at 

 present, the areas of acid volcanic rocks are confined to the vol- 

 canic belt which skirts the western margin of the Triassic sand- 

 stone in the eastern Piedmont region,' and to several of the ex- 

 treme northwest counties' of the state. These rocks show no 

 essential differences, so far as they have been studied, from cer- 

 tain areas of similar ones which occur and are traced at irregu- 

 lar intervals northward along the Atlantic border region of 

 North America as far as Newfoundland. 



Of those occurrences in North Carolina, the quartz por- 

 phyry found near Charlotte is the only one visited by me that 



* George P. Merrill, Stones for Building and Decoration (New York, 1897), 

 2(1 ed., pp. 272, 273. 



' J. V. Lewis, Notes on Huilding and Ornamental Stone, First Bivnuial Re- 

 port of the State Geolof;ist, N. C. Geolofiical Survey, 1893, p. 10 j. 



' George II. Williams, "The Distribution of Ancient Volcanic Rocks Along 

 the Eastern Border of North America," lournal of Gcolot^v, Vol. II (1S94), pp. 

 1-32 ; J. S. Diller, "Origin of Paleotrochis," Amernatt Journal of Scieme, Vol. 

 VII (1899, 4th ser.), pp. 337-42. 



* A. Keith, Bulletin No. t6S, U.S. (leological Survey, p. 52; Ceoh\t;ii Atlas 

 of the United Stittes, "North C'arolina-Tcnncssec, C'ranfterry Folio," 1903. 



