136 PHYSIOGRAPHY. 



Pyroxene. 



most cases easily separated, and present striated faces of 

 composition. 



1. The present species embraces a large number of varieties, both 

 simple and compound, among which there exist uninterrupted transi- 

 tions. JLugile comprehends opake varieties, the colors of which are 

 black, or blackish green. One of its subdivisions, foliated A ugite, oc- 

 curs in imbedded crystals. Conchoidal Augite refers to imbedded 

 grains, whose fracture is perfectly conchoidal ; common Augite occurs 

 also in grains, but having an uneven fracture. Foliated Augite is trans^ 

 formed, by decomposition, into those earthy masses, which have been 

 called crystallized green-earth. Coccolite is of rather paler shades of 

 green colors than the preceding varieties, and consists of very distinct 

 granular particles of composition, which may be easily separated. The 

 colors of Sahlite, are generally paler green, and inclining to grey ; it is 

 faintly translucent on the edges, though there are some varieties of it, as 

 black and opake as Augite. It is compound, parallel to the face of P. 

 If the colors become very pale, it passes into Diopside, which contains 

 greenish grey, greenish white, &c. semi-transparent, crystals, or mass- 

 ive varieties, also of pale colors, and compound parallel to the face of r. 

 Baikalite cannot be distinguished from Sahlite, even by such slight 

 marks as those just quoted, and Fassaite is the name of those varieties 

 which unite the green colors of Sahlite, or some that incline still more 

 to yellow, with crystalline forms similar to those of Diopside. Ompha- 

 zite is a compact, leek-green variety, with an imperfectly conchoidal or 

 splintery fracture, and generally mixed with Garnet. That variety, 

 called Green Diallage, is grass- green, either crystallized or massive, 

 and in the latter case, it presents a granular structure, or is compound 

 parallel to P, or to r, alternating in layers, with particles of Hornblende 

 of the same color. Very delicate crystals produce a kind of Asbestus, 

 which is different from the one in connexion with Hornblende, and dif- 

 ferent also from Picrolite and Picrosmine.- 



2. Before the blowpipe, it melts pretty easily, and emits a few bub- 

 bles; it finally yields a glassy globule, more or less intensely colored by , 

 iron. It is readily dissolved by borax. Several varieties of the present 

 species have been obtained by way of fusion. Black crystals are not 

 unfrequent among the slags from the iron furnaces of Sweden. A white 

 variety, in perfect crystals, has been obtained by mixing silica, lime and 

 magnesia, in the necessary proportion, and exposing the mixture, in a 

 charcoal crucible, to the heat of porcelain furnaces. Many varieties of 



