PRECIOUS STONES. 



Frequently neither the hardness of a gem stone nor its 

 behaviour before the dichroiscope is sufficient to enable its 

 identity to be reliably known. In such a case its specific 

 gravity may settle the question ; but it must be confessed 

 this requires a more accurate balance than the prospector 

 may possess, and the advice of an expert may be necessary. 



Of all the different transparent or translucent minerals 

 there are only a few kinds of value, and so a knowledge of 

 the dichroism of all these in different colours and different 

 depths of colour should be acquired. 



TABLE OF CHARACTERISTICS OF VARIOUS STONES 

 AND GEMS. 



* When a stone to be tested for hardness is very small, it may 

 be placed in a hole at the end of a stick and pressure applied during 

 the test. 



