ALUMINA. 



317 



Near the village of Amity, it occurs of a greenish black to purplish grey colour. A mile 

 southwest of this, on the farm of I. Layton, is a locality remarkable for the number, variety 

 and large size of the crystals which have been procured. The colours are black, greyish 

 black, bluish black, and reddish brown ; the black, however, being the most abundant. The 

 crystals are usually very perfect, but sometimes exhibit the octahedral form of the molecules 

 of which they are made up, a kind of dissection having taken place. They are associated 

 with serpentine, chondrodite and crichtonite. 



Half a mile north of the preceding, spinelle occurs in greyish red octahedrons, and in twin 

 crystals. 



About half a mile south of the village of Amity, the brown variety has been found. Dr. 

 Heron has an imperfect crystal from this locality, weighing fifty-nine pounds. 



A mile north of this village, on the farm of W. Raynor, black spinelle is found in grouped 

 «nd twin crystals. 



There are also numerous other localities in the immediate vicinity of the village of Eden- 

 ville, in this town. For these, I must refer to the Catalogue of Dr. Horton.* 



The following crystalline forms have been found in this town, viz. Fig. 259 ; the grouped 

 crystals. Fig. 260 and 261 ; 



Fig. 260. 



Fig. 261. 



Fig. 259. 



The twin crystal. Fig. 262, consisting of 

 two equal and similar portions of a crystal 

 resembling Fig. 256, being sections parallel 

 with two opposite primary planes applied 

 base to base ; 



Fig. 263, composed of about equal parts 

 of the primary octahedron, of which one- 

 half is turned round ; 



Fig. 264, in which three nearly equal 

 parts of the same crystal are variously 

 turned upon each other. The face of com- 

 position, in the latter case, projects. 



'New-York Geological Rtporti, 1839. 



