OP ARTS AND SCIENCES. 



223 



chrysocolla, and some native copper, but as yet, even at a depth 

 of over two liundred feet, no sulphides have been discovered, — a 

 condition which is very unusual. 



" There is another form in which the azurite is found, which re- 

 sembles the Chessy deposits, that is, in a quartzose rock scattered in 

 nuggets varying from the size of a pea to that of a walnut. All the 

 ores carry, besides iron and silica, a small pei'centage of manganese 

 and alumina, together with an amount of zinc varying from two to 

 eight per cent." 



The specimens received at the cabinet of Harvard College con- 

 sisted of large masses of transparent crystals closely packed together, 

 accompanied by beautiful stalactites consisting mainly of azurite, 

 but coated over with malachite, the malachite usually covering the 

 azurite. 



Many of the crystals resemble 

 closely those from Chessy, being 

 grouped together so as to give a 

 general rhombohedral aspect, having 

 rounded faces and looking not un- 

 like saddle-back crystals. These 

 saddle-back crystals were all more 

 or less rough, dull, and opaque; but 

 with them were associated numerous ])rilliant transparent glassy crys- 

 tals elongated on the ortho-dingonal, having the general aspect shown 

 in the accompanying sketch (Fig. 1). 



Fig. 1. 



