NOME V. LAZULITE ROCK. 91 



quality was sold, in his time, at 20 dollars an 

 ounce, which is dearer than gold. 



" Dufay, of the Academy of Sciences, has 

 found the lapis when exposed to the sun, and 

 afterwards brought into the dark, to give a phos- 

 phoric light ; and that the purer and deeper the 

 blue, the stronger the phosphorescence. The 

 grey and white kinds have not this effect. 



" In some mineralogical systems, lapis was 

 classed with zeolite ; but a further knowledge of 

 the nature of these two substances, has again 

 separated them. 



" The lapis has sometimes been confounded 

 with the Armenian stone, which is totally dif- 

 ferent, and is nothing more than a fine moun- 

 tain blue, or oxyd of copper; and the colour 

 which is extracted from it, though fine at first, 

 has not the durability of ultramarine. 



" The analysis of lapis lazuli yielded to 

 Klaproth : 



" Silex 46 



Argil 14 50 



Carbonate of lime 28 



Sulphate of lime . 6 50 



Oxyd of iron . . 3 



Water 2 



100. 



