52 Chemical Examination of American Minerals, 



and may, therefore, perhaps be admitted to have once been 

 in a state of fusion. They consist essentially of silica and 

 magnesia. In pyroxene and amphibole, lime likewise enters 

 as a constituent, and not unfrequently oxide of iron. The 

 same thing happens with respect to hypersthene. 



Hypersthene constitutes an abundant ingredient in a beauti- 

 tul trap rock, to which the name o{ hypersthene rock has been 

 given. It occurs in the north of England, and constitutes 

 whole mountains of the most savage appearance, in that part 

 of the Isle of Skye known by the name of Cuchullin. It is 

 found also in large isolated crystals in the island of St. Paul, 

 on the coast of Labrador, on which account it was distin- 

 guished by Werner, by ihe name of Haulite. 



I thought it worth while to subject paulite and Isle of Skye 

 hypersthene, to a chemical analysis. Paulite had indeed 

 been already analyzed by Klaproth ; but I am not aware that 

 hypersthene, from Isle of Skye, has been hitherto examined 

 by any chemist. 



Paulite is black without any shade of green. Hypersthene 

 is also black ; but the surface of the crystal is splendent, and 

 exhibits a false metallic lustre, somewhat similar to bronze. 

 All the specimens of paulite which I have seen, are rrystal- 

 ized so irregularly that the shape cannot be made out. But 

 the Isle of Skye hypersthene, is frequently in pretty regular 

 crystals. They are four-sided prisms, w th angles of 87° and 

 93**, which are very nearly the angles of pyroxene. I have 

 never met with a crystal in which the summit of the prism is 

 well defined. I do not, therefore, know whether the prism be 

 right or not. 



The specific gravity of paulite I found, 3'.385. 

 The specific gravity of hypersthene, 3'338. 



Klaproth gives the specific gravity of Paulite 3*390. 



The hardness of both varieties, as far as I can make out, 

 is precisely the same ; and very nearly, if not exactly, equal 

 10 that of arfvedsonite. 



