216 UNIVERSITY OF VIRGINIA PUBLICATIONS 



those made up of a less number of parts, such as trillings and f ourlings being 

 not uncommon from the Georgia locality. 



The three following analyses quoted by Hintze serve to show the essen- 

 tial chemical composition of the Graves Mountain rutile. 



Analyses of rutile from Graves Mountain,' Georgia. 



TiO. 97.22 97.52 97.64 



FeiOs 2.62 2.64 2.61 



99.84 100.16 100.25 



While coarse rutile was not observed at this localitj^ by the senior author, 

 careful examination of the dumps alongside the numerous openings on the 

 northwest slope of the mountain from which the mineral was mined, and 

 the presence of rutile in microscopic proportions in thin rock slices, clearly 

 indicate the rutile matrix to be a heavy, dark-colored rock, composed of an 

 aggregate of long bladed and coarsely columnar crystals of cj'anite and 

 massive granular hematite, with usuallj^ some quartz. Frequently the 

 rock is composed of excessive hematite "with less C3'anite, and as often cj^an- 

 ite may predominate. In either case the rock presents a more or less porous 

 texture which perhaps is most pronounced in specimens showing dominant 

 cyanite. Professor Shepard's description of the occurrence of rutile in 

 this rock follows. He says:* 



The central part of the mountain, to the thickness of 50 feet, is composed of a hema- 

 titic rock, which includes in some places an abundance of a ferruginous kyanite, much 

 resembling in appearance the diaspore from the Urals. With the kyanite is found 

 rutile, often in gigantic crystals (weighing upwards of a pound), and possessed of 

 much regularity of crystalline form. The prevailing figure is a square prism with 

 truncated lateral edges, and surmounted at both extremities by an eight-sided pyra- 

 mid. There is also found a most remarkablj' perfect twin crystal, in which the 

 geniculation is six times repeated, — producing an hexagonal prism, surmounted at 

 each end by a six-sided pyramid, with a reentering, six-sided hopper-shaped cavity, 

 at the tips. These crystals are all more remarkable for their sj^mmetry and polish, 

 than any I have ever seen. Some are fully equal in lustre to the brilliant crystals of 

 cassiterite from Cornwall or Bohemia. The most perfect rutiles are generally im- 

 bedded in the massive kyanite ; and when detached leave behind impressions having 

 a polish and lustre equal to that of their own planes. A little common quartz is also 

 mingled with the kyanite and rutile. 



Closely associated with kyanite, rutile and quartz, are considerable masses (8 or 

 10 inches thick) of a mineral known among the miners of Georgia as steatite, but which 

 is true pyrophyllite, — differing in no respect from that of the Urals, except in the finer 

 stellulations it presents, and in the slight ferruginous stain it exhibits near their 

 centres. 



* Op. cit., 1859. 



