152 



Component 

 parts. 



BohemiaB 

 jarnet. 



STAUROLITE. 



The component parts of the melanite were found to be 



Silex •. 35-5 



Lime 32-5 



Alumine - 6 



Oxide of iron 24'25 



■ - manganese 0*4 



98-65 



This analysis agrees very closely with that of Vauqnelin. 

 The melanite differs greatly therefore from augite, and par- 

 ticularly in containing no magnesia. 



In a note Mr. Klaproth observes, that his analysis of the 

 Bohemian garnet, now called pirop, has been given in se- 

 veral French works as his analysis of the melanite ; and he 

 has found, since the publication of the 2d volume of his 

 Essays, that about 2 per cent of chromic acid should be 

 added to the component parts of the Bohemian garnet as 

 there given. 



Cruciform 

 schoerU 



Red. 



Brown. 



'iilaik. 



Analysis of the siaurolite [staurotide of Haiiy), 



Mr. Klaproth has analysed two varieties, one red the 

 other black, both from St. Gothard. 



The proximity of the red staurolite to the cyanite is very 

 remarkable. These two substances are frequently crystal- 

 lized together, so as apparently to form but one stone. 

 When this is the case, the staurolite becomes a little trans- 

 lucid at the end of the prism. 



The brown staurolite of Quimper, in the department of 

 Morbihan, as well as that of Finistere, in France, serves as 

 a connecting link between the black and red varieties. In 

 this country conjoined crystals are much more common 

 than single ones ; and they commonly cross each other at 

 right or at oblique angles {the staurotide rectangulaire and 

 obliquangle ofHdiiy). Frequently the crystals joined to- 

 gether are of the same size; but often one is smaller than 

 the other, and seems implanted in the larger. 



The specific gravity of the black staurolite was 3*51. It 



experienced 



