Gibbs on Tourmalines^ ire, 347 



The tourmaline is found of almost every colour, and this 

 variety of colour caused at first a number to be formed inta 

 new species ; which are now considered only as varieties of 

 the tourmaline : such as the rubellite, the tourmaline apyre, 

 and indicolite. 



The different analyses of the tourmaline, however, affords a 

 greater variety of results than is known in almost any other 

 mineral. 



The specific gravity of the black varies from 3.08 to 3.36 



Green . from 3.15 to 3.36 



Red . from 2.87 to 3.10- 



Analysis gives Silex from . . 35 to 58 



Alumine . . . 20 to 48 



Magnesia . . to 10 



Iron .... to 23 



Manganese . . to 13 



Alkali ... to 10 

 Water ... to 4 



These differences must be in some measure ascribed to a 

 defect in the accuracy of some of the analyses. But it appears 

 that iron has not been discovered in the red tourmaline. It is 

 not unworthy of notice, that the red tourmaline is considered 

 as infusible, but the others fusible. 



The red tourmaline has been the most valued, from its 

 scarcity, its employment in jewelry, and the beauty of its 

 crystals. It has been discovered in Siberia, in Moravia, in 

 the East-Indies, and in Massachusetts. In Siberia it is found 

 in a vein of decomposed feldspar in a fine-grained granite, with 

 black tourmaline. In Moravia with quartz and lepidolite (or 

 rose-coloured mica) in gneiss. In the East-Indies, at Ava and 

 Ceylon, but its geological situation is not known, though it is 

 probably in gneiss or granite. 



could not determine. He haa devoted a long life to the iraprovenaent of science f 

 and if is his praise, that he has preserved the meekness of religion amidst the 

 most flattering success. Our scientific countrymen, who have visited Paris, have 

 been particularly indebted to him ; and this notice is, In their behalf, both th® 

 '-ibute ef justice and gratitude 



