3G8 ANNALS NEW )(>h'l< ACADIhUY OF SCIENCES 



structure. In tlie larger and more ehaiaeteristic specimens, the curious 

 combination appears of a radiated nodule with a distinct general crystal- 

 line form. The nodules are seen to be pyramidal in shape and sub- 

 triangular ill outline, expanding to a convex base or termination uliicli 

 shows distinctly in many cases not a mere sphciiral convexity but the 

 characteristic low rhombobedral termination so familial- in tounnaline 

 crystals. This peculiar com1)ination is unkiiown to me from any other 

 locality, and has seemed worthy of special notice. I presented a descrip- 

 tion with specimens before the New York Mineralogieal Club at its meet- 

 ing in November last, and now desire that it be laid before the Academy. 



These crystalline nodules are single developments, not fragments from 

 spherical masses, as might at fii'st be supposed from their pyramidal 

 form; but the termination is entirely too convex for this supposition. 1 

 regret very much that T do not know exactly their mode of oceui-rence. 

 They are found loosely scattered through the soil and )ii-ol)al)ly come 

 from gneisses or mica schists at a greater depth, but no specimens have 

 reached me that show any portion of attached matrix. Professor "Watson, 

 the State Geologist of Virginia, inclines to the view that they are derived 

 from pegmatites; but he has not seen the specimens themselves and has 

 no positive evidence. Their mode of occurrence is one tliat is extremely 

 familiar in the south where the countr}^ rock is weathered and decom- 

 posed sometimes to great depths, forming the surface mantle of so-called 

 "southern drift,*' in which are distributed the harder jind moi'e resistant 

 minerals that have been liberated in the decay of the matrix. 



Most of the specimens which 1 obtained from Mr. Porter have been 

 placed, together with all my other southern material, in tlie "Piedmont 

 Collection" of minerals of the South Atlantic states which 1 am engaged 

 in forming at the Charleston (S. C.) Museum; but T furnished Mr. 

 Gratacap of the American Museum at New York Avith a few characteristic 

 examples. 



The precise locality of these specimens as given by ^Ir. Porter is Tye 

 Eiver, Nelson Count}^ Va. 



This peculiar form, a radiating nodule, possessing also the triangular 

 contour and the rhombobedral termination of a tourmaline crystal is, 

 so far as I know, peculiar to this locality, and 1 have deemed it worthy 

 of special description. 



The Section then adjourned. 



P. B. Kaki.r. 

 Secretary pro tern. 



