NOMt VI. OBSIDIAN. 



445 



Ins as the obsidian of the ancients, is a volcanic 

 amel of the province of Quito. 



" The volcano of the isle of Bourbon presents Bourbon, 

 very remarkable vitreous ejections: they are fila- 

 ments of a flexible and yellowish glass, two or 

 three feet in length, sprinkled at intervals with 

 small globules. These threads of glass showed 

 themselves in the eruptions of the 14th of May 

 1766, and the 17th of July 1791. In the latter, 

 they were carried by the winds, and strewed 

 upon the trees, to the distance of ten leagues. 



" The ancient volcanoes of northern Asia 

 have also produced vitreous substances. Near 

 the port of Okhotsk, in the gulf of Kamschatka, 

 there is a volcanic hill called Marikan, formed Marikan. 

 of a white sand entirely vitreous j and in which 

 are found dispersed, globules of glass and vol- 

 canic amel. This very remarkable sand ap- 

 pears at first view to be shelly ; for it is all com- 

 posed of white fragments, resembling mother of 

 pearl, convex on one side and concave on the 

 other. These fragments proceed from the re- 

 mains of a singular variety oT vitreous globules : 

 they are at most of the size of a pea, of a pearly 

 white, perfectly spherical, and exactly like 

 pearls. They are entirely composed of con- 

 centric layers, as thin as the peel of an onion, 

 and which separate from each other. They are 



