Genth.] dJ4: [y e p_ 15>5 



of this fine scaly granular chlorite, and another one, which I shall copy 

 for comparison (c. 3) has lately been published by A. R. Leeds, in his 

 contributions to mineralogy.* 



d. The Culsagee Mine, near Franklin, North Carolina, has furnished a 

 great variety of specimens of extraordinary interest- 

 There are some, which are aggregations of dark green foliated chlorite, 



having distinctly visible the rough outlines of hexagonal crystals of 

 corundum, and in their centre the unaltered mineral ; others again are 

 more irregular in shape, and appear to have been fragments of massive 

 corundum before they were converted. The nuclei of unaltered corun- 

 dum, are often free from any admixtures, often, however, containing 

 through their mass laminae of chlorite, at times in large quantities. 



But there are frequently specimens met with containing perfect and 

 brilliant crystals of corundum, which appear to have formed after a great 

 portion of the original corundum had changed into chlorite, as if there 

 had been an excess of alumina ready for combination, which, not finding 

 a supply of the requisite amount of silicic acid and bases, had again 

 crystallized as corundum. 



The chlorite in immediate contact with the unaltered minerals, whether 

 corundum or spinel, has often a fine scaly pseudo-fibrous structure, which 

 at a greater distance assumes the more laminated shape ; however, a 

 great portion is laminated, where it touches either spinel or corundum, 

 and in reality some of the largest plates, three or four inches in diameter, 

 contain a considerable quantity of corundum disseminated through their 

 mass. 



The following varieties from the Culsagee Mine were analyzed ; broadly 

 foliated dark-green (dl) by myself, (d2 and 3) by Mr. Thos. M. Chatard, 

 and a fine scaly variety diverging from corundum, (dA and 5), by myself. 



e. Similar nuclei of unaltered corundum in foliated chlorite have been 

 observed amongst the specimens from Shooting Creek, Clay County, 

 North Carolina. 



The decomposed chlorites from Unionville gave : 



Si0 2 = 



A1 2 3 = 



Fe 2 3 = 



MgO 



Ignition = 



98.22 100.12 



The oxygen ratio of RO : Rj0 3 : Si0 2 : ELO is very near = 1.5 : 

 3 : 3.5 : 2.5, which can be expressed by the formula : 2(3 RO, 2 Si0 2 ) 



*A. R. Leeds, Sill. Journ. [3] VI, 25. 



