GEOLOGY OF GRAVES MOUNTAIN 



211 



Analyses of pyrophyllitc from Graves Mountain, Lincoln County, Georgia, and Chester- 

 field district, South Carolina. 



I corresponds to the formula 



H20.Alo03.4Si02 or HoAl^SiiOij 

 I. Pyrophyllite in yellowish stellate or radiate aggregates collected by Thomas L. 



Watson from Graves Mountain, Lincoln County, Georgia. J. Wilbur Watson, 



analyst. 

 la. Ratios from I. 

 II. Pyrophyllite in radiated aggregates with lazulite and cyanite from Chesterfield 



district, South Carolina. F. A. Genth, Amer. Journ. Sci., 1854, vol. 18, p. 



410. Quoted by Dana, E. S. A System of Mineralogy, 1900, p. 692; and 



Hintze, C. Handhuch der Mineralogie, pp. 829, 831. 



Lazulite. Lazulite is a rather rare mineral, a phosphate of alumina 

 containing some magnesia and protoxide of iron, corresponding to the form- 

 ula (A10H)2(MgiFe)(P04)2 in which the ratio of Fe : Mg(Ca) varies from 

 1 : 12 to 2 : 3.* The known localities in which the mineral occurs in the 

 United Statesf are hmited to three in North Carolina, and one each in 

 South Carohna and Georgia. The North Carolina localities include Clubb 

 and Crowder mountains in Gaston County, and Sauratown in Stokes 

 Countjr, the South Carolina locality includes the Chesterfield district, and 

 the Georgia locality is Graves Mountain in Lincoln County. The mode of 

 occurrence, including kind of rock and mineral associations, is similar for 

 the localities in Gaston County, North Carolina, and Lincoln County, 

 Georgia, except that corundum which is unknown in the Georgia locality 

 is an associate in the North Carolina localities. According to Genth, J the 



* Dana, E. S., A System of Mineralogy, 1900, pp. 798-799. 



t Mr. Frank L. Hess of the U. S. Geological Survey informs the senior author that 

 he has received massive specimens of lazulite from California. No published 

 description of the locality has appeared and, so far as we are aware, nothing is 

 known of the exact occurrence of the mineral. 



t Genth, F. A., Amer. Journ. Sci., 1854, vol. 18, p. 410. 



