ON THE \ENITE OF RHODE ISLAND. 479 



If we adopt the primitive fonu oljtaincd l)v meclianical 

 division by Hauy, which is a icctang;iilar octaedron, we shall 



have for representative signs 4 F 4 B ; and adopting the hy- 



1 

 s r 



pothetical nucleus of Cordier, which is a straight rhoinboi- 

 dal prism, its representative signs would be 4G4 V. 



s P 



The specimen now in the collection of the Society is coni- 

 posed of a few of the above described crystals placed in an 

 horizontal position, with crystals of greasy quartz, on gra- 

 nular quartz, containing some minute octacdrons of magnetic 

 iron ore which make it act upon ihc nragnetic needle. 



I found some moditications of the same form on the spe- 

 cimens which 1 received from Dr. Rol)inson. Some of the 

 prisms are joined side by side, so as to form an even plane 

 which might be taken for an extensive tabular crystal ; but 

 when examined by a magnifying glass, we perceive the joints 

 by which these different prisms are united. Some of these 

 tables are terminated by a plane under an angle of 90^, and 

 must therefore be composed of the prisms above described. 

 Others are terminated by an angle of between l-l-j^and ioO^ 

 which I have not been al)le to ascertain owing to the position ; 

 so that it is probal)le that at this locality some other forms 

 may l)e discovered. 



The Yenitc is generally of a black colour ; as is the case 

 with the European mineral. But that of Rhodi- Island oilers 

 also a greyisli wliitc, intermixed with yellow and passi.ig 

 from that through the various shades of rul)iginous yellow 

 and blown to |)erfect black. However these coIoim's arc 

 rare. I have but one specimen in my collection, and it is 

 the only one that I have seen. 



It occuis likewise in Ihc quartz already mentioned ; and in 

 limestone of a peach blossom led colour, |)rol)a'>lv coloin'cd 

 by manganese and some green fibrous sul)3faiice which 

 seems to be the acicular actinolite and limestone, which has 



