46 



becomes pearly, the nuclei seem to be separating and curv- 

 ing from about the angle of 30° to about 20°; see the 

 figures. They mostly appear of the natural pearly lustre, 

 but are often at length more curled and darkened, and thence 

 may be called spathose iron ores : perhaps they may be called 

 iron ores whenever the common browner aspect seems to 

 indicate as much. Those, however, which have the forms 

 and fracture of crystallized carbonate of lime may be placed 

 as such while they retain the whitish pearly lustre. 



Pearl spar analysed by Bergman contains 



Lime 38 



Oxide of iron 38 



Oxide of manganese 24 



100 



By Wolf, 



Carbonate of lime 60 



Oxide of manganese 35 



Iron 5 



100 



By Berthollet, 



Carbonate of lime 96 



Oxide of iron and manganese . . 4 



100 



Thus different analyses, showing a difference in the pro* 

 portion of the substances of which it is composed, decide 

 it to be more or less an (iron ore. 



