OP ARTS AND SCIENCES. 49 



in Pennsylvania. Professor J. Lawrence Smith, in his recent article 

 in Am. Jour. Sci. (III. vi. 180), says that "in the development in 

 North Carolina the corundum " (with which the vermiculite is associated) 

 "occurs in chrysolite or serpentine rocks, and outside of serpentine it 

 has not been found. These chrysolite rocks belong to a regular system 

 of dikes which have been traversed for the distance of about one hundred 

 and ninety mUes. This system of dikes lies on the north-west side of 

 the Blue Kidge, and has a strike parallel to the main mass of the 

 ridge, and has an average distance from the summit of the ridge of 

 about ten miles. The serpentine appears at intervals along this whole 

 line of one hundred and ninety miles," and " is usually enclosed in a 

 hard crystalline gneiss." In the serpentine the corundum has been 

 found at several localities along a distance of forty miles. Colonel 

 Jenks writes me : " The workmen have opened a new vein they call the 

 gem vein. It is walled with chrysolite, and the fissure is from one to four 

 feet wide, which fissure is filled with ripidolite, and in this the corundum 

 crystals are imbedded." As regards the association of the ripidolite and 

 vermiculite, he also writes : " They occur both alone and intermingled, 

 and also in layers, like the leaves of a book." Again : " The ripidolite 

 maintains a uniform character of texture and appearance, whether 

 associated with the vermiculite or alone. In the vein at the bottom of 

 the shaft I have spoke of, and elsewhere, it is of uniform liardness, 

 texture, &c., but in it the corundum seems to have lost cohesion, — in 

 some localities falling to pieces, and crumbling out of the ripidolite 

 matrix. But, when exposed to the air and sunshine for a day or two, 

 the corundum regains its cohesion, and you can then chip off the ripid- 

 olite from it. It is just the opposite with the vermiculite when alone 

 the matrix. Sometimes it occurs in masses, several feet long, formed 

 of scales as large as your hand, easily separating like mica from the 

 corundum, which in this matrix always seems to retain its cohesion. 

 Then, again, the vermiculite will occur in masses of many bushels, all 

 broken up and disintegrated, like very coarse bran, in which the crystals 

 of corundum lie like eggs in a box of sawdust. The great crystal 

 (weighing 316 pounds) was thus deposited. At other places the entire 

 mass seems to have changed to the color of white Castile soap, with 

 specks of green in it, the corundum crystals all falling apart until 

 exposed, when they harden." This untechnical language of an unpro- 

 fessional but accurate observer conveys a very vivid idea of the mode 

 of association of these minerals. The specimens so kindly sent me by 

 Colonel Jenks confirmed in all respects his observations. In several 

 cases the corundum was still imbedded in both the ripidolite and the 



VOL. I. 7 



