404 



Miscellanies. 



at least its discovery has been alleged, and that in a doubtful manner, 

 in but three or four localities. This aerolite resembles, on the contrary, 

 in a remarkable manner, some of the slags of the furnace. Examined 

 with a strong magnifier, two distinct minerals are recognized : one im- 

 perfectly lamellar, presents in some parts bands analogous to those 

 which characterize the hemitropic masses of albite or labradorite : the 

 other, of a vitreous fracture, might be taken for quartz, if we did not 

 know from numerous observations, that this mineral is not found in true 

 volcanic rocks, nor in those of meteoric origin. Besides these two min- 

 erals, the eye detects small black glassy globules, analogous to perlite. 

 These are evidently the product of fusion, and their gray interior, which 

 is like the general texture of the stone, has not been altered by the heat. 

 Finally, there are to be detected small shining black plates, which are 

 particularly collected about the veins which traverse the stone. These 

 small plates resemble the scales of graphite which exist in some varie- 

 ties of gneiss. The gravity of the stone is 3.56 : that of the grains of 

 metallic iron, extracted by the magnet, is 6.48. 



Before the blowpipe, a fragment is immediately reduced to a black 

 hollow scoria, like that of the exterior crust of the stone. This proves 

 that the crust is the result of the fusion of the exterior parts, which are 

 oxidized to a veiy high degree by their contact, when at an elevated 

 temperature, with the atmosphere. 



M. Dufrenoy gives the following as the result of three analyses which 

 he made. 



Silica, 38.13 



Magnesia, 



Protoxide of iron. 



Protoxide of manganese, 



Alumina, 



Lime, 



Metallic iron, 



Nickel, 



Sulphur, 



Potassa, . 



Soda, 



17.67 



29.44 



a trace. 



3.82 



.14 



7.70 



1.55 



.39 



.27 



.86-99.97 



Or, grouping together the elements which are combined : 



Alloy of iron and nickel, .... 9.25 



' Pyrites, .67 



Ferruginous peridote, soluble in acids, . . 51.62 

 Matter insoluble in acids, and not related to any 



known mineral, 38.17—99.71 



Ulnstitut, July 22, 1841, No. 395. 



