296 DESCRIPTION OF THE MUSEUM. 



dull. It is used in polishing different substances, 

 such as metals and looking-glasses. After the 

 corundum comes the cymophane, which is \ery 

 brilliant, and of a greenish yellow; with lapi- 

 daries it bears the name of chrysoberyl and orien- 

 tal chrysolite. The spine lie which follows, fur- 

 nishes two varieties of ruby, found in commerce 

 under the names of the spinelle and ruby balais, 

 and which only differ in the deepness of their 

 colour. 



The emerald is also much sought after for the 

 purpose of ornaments. The precious stones be- 

 longing to this species are the emerald of Peru, 

 and the beryl or aigue-marine. We, see on the 

 stage for study, a fine crystal of emerald from 

 Santa Fe, which presents the primitive variety. 

 The Peru emerald is the most esteemed, it is of a 

 pure deep green. The beryl is of a greenish blue, 

 or of a honey yellow. Below the stage are some 

 long cylindrical crystals belonging to this variety, 

 and which come from Siberia. We find in 

 France, opaque emeralds of a considerable size, 

 but which are of no value : such is the enormous 

 crystal, placed in the lower part of the case, 

 found at Barat, near Limoges. 



After the emerald, we see the cordierite; 

 amongst its varieties is the water sapphire of the 

 jewellers. The name of cordierite is a compli- 



