1818.] VICINITY OF PHILADELPHIA. 463 



Red Oxide of Copper. Cuivre oxidule. H. i?w% Cop^ 



per. W. 



Beautiful capillary crystals, translucent and of a bright 

 red colour, have been lately discovered by Messrs. J. 

 Lukens and B. Say, at the same place with the two 

 former specimens. 



Copper Ft/rites. Cuivre pyriteaux. H. Yellow Cop- 

 per, Aiken. 



It occurs in amorphous masses, of a brass yellow co- 

 lour and often externally iridescent, at Perkiomen, and on 

 Chester creek, near a saw mill, three miles west of Ches- 

 ter, in Delaware county. At the latter place it exists in 

 quartz, accompanied with sulphuret of molybdena. 



Magnetic Sulphuret of Iron, Fer sulphure ferrifere. H. 



This mineral occurs amorphous, in the hornblende 

 rocks near the engine at Morris hill, and in small quan- 

 tities. 



Magnetic Oxide of Iron, Fer oxidule, H. Magnetic 

 Iron Ore. W. 



We find this on the Schuylkill in small quantities, of 

 a dark iron black, and possessing a slight metallic ap- 

 pearance. It is strongly attracted by the magnet. A va- 

 riety, known by the name of octaedral iron, should be 

 mentioned here. It is crystallized in regular octaedrons 

 from one sixteenth to one half of an inch in diameter. 

 Some of these crystals divided parallel to either face, and 

 transposed or partly turned round, form macles of tri- 

 angular formed tables, with their three sides bevelled, each 



