PHYSIOGRAPHY. 



Hornblende. 



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Green Diallage or Smaragdite, in some cases consists of laminae of 

 Hornblende, with faces of composition parallel to s ; in others, of the 

 same, alternating with laminae of Pyroxene ; both generally of bright 

 green colors. 



Among the varieties of this species, and those of Pyroxene, a striking 

 analogy of certain varieties has been observed. Augite and Hornblende, 

 Sahlite and Actynolite, Diopside and Tremolite, stand in these relations ; 

 and both series terminate in their respective kinds of asbestus. 



2. Before the blow-pipe, Hornblende melts with a little difficulty, at- 

 tended by a slight degree of intumescence, into a globule, which is not 

 clear, but variously colored by iron or chrome, agreeably to the contents 

 of the specimen. In borax, it also fuses slowly. 

 3. Jlnalysis. 

 By BONSDORF. By VAUQUELIN. 



4. Imbedded crystals of basaltic Hornblende often accompany those of 

 Pyroxene in basaltic and amygdaloidal rocks. Crystals of Hornblende 

 and of Tremolite, are found in limestone and dolomite rocks, as well as 

 in porphyry and granite. Common Hornblende, Actynolite, and Tre- 



cohering with each other, and easily separated ; into common asbestus, 

 relating to coarser varieties, more firmly cohering, and yielding splintery 

 fragments ; into Rock-cork, in which the particles are aggregated in a 

 loose felt-like texture ; and into Rock-wood or ligneous asbestus, in 

 which a texture of the preceding kind, only more firm and close, as- 

 sumes the appearance of dried wood. 



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