1883. 149 Trafis. N. V. Ac. Set. 



presence of sulphur and nitrogen is an additional indication. Still 

 these facts are not decisive, since sulphur and nitrogen occur also in 

 plant tissue, and the soft material of seaweeds becomes so broken 

 down by decay that its structure readily disappears. We cannot 

 but believe that we must credit part of the carbon in some lime- 

 stones to vegetable matter ; and this may be true of the clouded 

 marbles, presenting dark lines on a white ground, with wavy struc- 

 ture due to mechanical violence. Carbon often occurs in marbles 

 as graphite, which is the residue from the distillation of hydro- 

 carbons. Its quantity is sometimes small, but sometimes sufficient 

 to color them even absolutely black. In metamorphism the carbon 

 largely disappears, so that the graphite remaining may represent but 

 a tenth part of that originally present. At Newport, R. L, films of 

 carbon occur, converted into graphite, covering the impression of 

 ferns, etc. Graphite is also capable of condensation and segre- 

 gration, as illustrated by the graphitic carbon in cast iron, sometimes 

 beautifully crystallized in cavities. Here it has been plainly derived 

 from the carbon of the coal, i. <?., it is really of organic origin. 

 So also in limestones beautiful crystallizations of carbon occur, the 

 conditions having been favorable for its crystallization along with 

 other crystallized minerals, e. g., pargasite, tremolite, etc.; thus the 

 purest of all graphites have been formed. 



Dr. P. De p. Ricketts then made an exhibition of specimens, 

 and spoke on the subject of 



CERTAIN ORES FROM NORTH CAROLINA. 



(Abstract.) 



Dr. Ricketts fiist gave an account of a visit to Fisher Hill, near 

 Greensboro, N. C. 



The country rock there is crossed by veins of quartz, with dykes of 

 dioryte. 



Reference was also made to a visit to some mines in Montgomery 

 County, where the gold is native to a much greater depth than in the 

 case of the Fisher Hill veins, and occurs along the line of contact be- 

 tween a silicified slate and quartzyte, the latter forming what might be 

 called the hanging wall of the vein. The gold occurs native in thin 

 films in zinc blende, which is associated with galena, and iron and cop- 

 per pyrites. The richest portion of the deposit is along the line of the 

 hanging wall mentioned ; but the seams are very thin and uncertain. 



A visit to some copper deposits in Person and Granville Counties 



