OF ARTS AND SCIENCES: AUGUST 12, 1863. 1G7 



This specimen was detached from a mass weighing one hundred 

 pounds. It was found on the surface of the earth in the Dacotah In- 

 dian country, ninety miles from any road or dwelling. Owing to a 

 natural fissure in the mass, and its columnar structure, it was found 

 practicable to divide it by aid of a sledge-hammer. It was supposed 

 in Dacotah that this metal was some alloy of silver, on accoimt of the 

 remarkable whiteness of some portions of the mass, and it was sent to 

 Boston to be assayed for silver. The specimen was at once recognized 

 as meteoric iron, and a subsequent analysis confirmed that conjecture. 

 Native metallic iron in large masses has not yet been recognized on 

 this planet, excepting when it is of meteoric origin. Masses which have 

 been seen to fall from the heavens have been found to contain an alloy 

 of iron, nickel, tin, chrome, phosphorus, and occasionally a little sulphur 

 and iron have also been detected in them. 



Chemical analysis of the Dacotah meteorite gave the following re- 

 sults : — 



Specific gravity 7.952. 



Metallic iron, whiter than artificial iron ; has in some places a hard- 

 ened crust on the surface, but internally files quite soft. 



98.340 98.888 



No chlorine, sulphur, or copper was discovered in this meteorite. 



Dr. Jackson also exhibited some beautiful and perfect crys- 

 tals of green felspar, or Amazonian stone, from the granite 

 quarries of Rockport, Massachusetts. 



This mineral was first discovered at Rockport by Rev. S. Barden of 

 that town. He subsequently discovei*ed purple fluor-spar, small crys- 

 tals of zircon, and very large and handsome crystals of smoky quartz, 

 equal in beauty to those found near Mount Saint Gothard in Switzer- 

 land. Recently, Rhodonite or red bi-silicate of manganese and Fer- 

 gursonite, a compound of oxides of tantalium, ytti'ia, and cerium, have 

 been discovered by Mr. Barden, and determined by the analyses of Dr. 



