44« 



ON THE TOPAZ OF SCOTLAND. 



not so hard as spinelle. Specific gravity 3,570* 

 (Thomson.) 



This crystal weighs 7 ounces 3 pennyweights 

 18 J grains Troy ; and a fragment of a crystal 

 from the same tract of country, now in the posses- 

 sion of Mr Farquharson of Invercauld, weighs 1 

 pound 3 ounces 8 drams, and 8|- grains Troy 

 weight. 



These are the largest topazes hitherto found. 

 In the National Museum at Paris, which is the 

 most extensive in Europe, the largest topaz is one 

 weighing 4 ounces 6 gros *. 



The discovery of so valuable a gem in this 

 country, naturally leads us to inquire, in what si- 

 tuation it is found, and whether or not it is likely 

 to occur in considerable quantity. Unfortunate- 

 ly, the data for answering these questions are not 

 complete : we must, therefore, at present rest sa- 

 tisfied with a short statement of the geognostic re- 

 lations of the topaz of foreign countries, which, 

 when compared with the accounts given of our to- 

 paz, will enable us to guess at its probable geo- 

 gnostic situation. 



This gem occurs in considerable quantity in the 

 Electorate of Saxony, in a particular species of 

 moufttain-rock, denominated, by Werner, Topaz- 

 rock, because topaz is one of its essential consti- 



* It is said that there is a topaz in the rich collection 

 of Sir John St Aubyn, the size of a list. 



